GSC is often perceived as the stalliest metagame, and while the characterization of it as "all stall" is definitely misguided, it is true that Pokemon generally take more hits than usual. There's Leftovers everywhere, everything can have max defensive stats and still have enough Speed and Attack to scare things off, everything runs Rest and can generally live through it, and Sleep Talk users can use Rest when sleeping. Clearly, passive damage is more important here than in any other generation to get enough damage to score KOs, but there's no Sand Stream, Leech Seed is nerfed relative to future generations and is pretty uncommon, and Toxic resets upon switching out, not to mention that everything runs Rest to undo Toxic anyway. However, GSC does have one common source of passive damage: Spikes. Unfortunately, you only get one layer in GSC, but that's not to say that Spikes is merely a nuisance in GSC. Just because they aren't wearing things down and sometimes outright killing things as quickly as they do in future generations doesn't mean they aren't having an impact. Au contraire, the aforementioned necessity of passive damage and the lack of other good sources of it make GSC arguably the most effective generation for Spikes, even if the effect of the move itself is at its most subtle.
Most sources of passive damage in GSC suffer from one crippling flaw: namely, that they aren't forever. Spikes, on the other hand, stay on the opponent's side of the field until Rapid Spin is used, meaning that the opponent can't just Rest them off like Toxic. However, both Spikes and the similarly-important Rapid Spin receive very poor distribution, and ultimately running a Spiker or spinner results in a loss of offensive or defensive team synergy. There are really only three Pokemon that commonly use Spikes or Rapid Spin, so the Spikes metagame revolves around those three, although there are a few unconventional options that can work as well. Without further ado, the main Spikers and spinners in GSC are as follows.
Cloyster is probably the best Spiker in terms of giving up the least offensive synergy. With Explosion and STAB Surf to ensure that those Pokemon that resist Explosion are kept at bay, Cloyster is a major wallbreaking threat. In addition, its high Defense and STABs let it serve at least as a temporary check to Marowak, Steelix, and Rhydon, so it is not without its contributions to defensive synergy.
In terms of the actual Spikes game, however, Cloyster is a bit flawed. First, while both Spikes and Rapid Spin are in its movepool, it cannot use Rapid Spin in conjunction with Explosion. Thus, Cloyster must make a choice between offering offensive synergy and being able to keep Spikes off one's own side of the field, which in turn has major implications for how fast- or slow-paced one's team can be. Second, Cloyster has glaring special weaknesses and a vulnerability to Toxic, and is also dead weight while asleep to make Rest a non-option for it unless it is paired with Heal Bell support. Thus, it can struggle to find opportunities to switch in, and it can easily lose the Spikes war by failing to outlast the opponent's Spiker or spinner. Finally, and perhaps most glaringly, it has almost no way through its own efforts to keep Spikes against Starmie, the game's premier spinner (read more about Starmie below). This means that if you're depending on keeping Cloyster's Spikes down, you need to run specific support to do so on a consistent basis—for example, you should use Misdreavus to spinblock instead of Gengar unless you're absolutely sure you can play around Gengar's Psychic weakness.
Forretress is a lot more specialized than Cloyster is. Forretress doesn't offer anywhere near the offensive or defensive synergy that Cloyster does, as it doesn't have good STABs for forcing plays. In addition, Forretress loses to Cloyster one-on-one in the short run since it is 3HKOed by its STAB Surf. However, Forretress does not have Cloyster's most glaring weaknesses in the Spikes game. For starters, it can run both Explosion and Rapid Spin on the same set, so it doesn't have to choose between having the ability to kill setup sweepers in case of emergency and being able to spin away Spikes. Second, it's got a nice Toxic immunity to give it the longevity it needs to outlast the opponent's Spiker or spinner in the long run (even a Cloyster if you manage to land a Toxic on it). Finally, with Hidden Power Bug it can 2HKO Starmie, meaning that it doesn't need specific support to keep Spikes against it.
However, Forretress is not without its own problems in the Spikes game. While it, unlike Cloyster, can afford to stay in against most Exeggutor, most Gengar, and most mixed sweepers, it is afraid of possible OHKOs by Fire moves, thereby forcing it to scout the opponent's sets for possible Fire moves before it attempts to set up on them. Furthermore, it doesn't take Water moves as well as Cloyster and cannot switch in to counter the likes of Marowak and Rhydon. Therefore, Forretress doesn't switch in to set up Spikes any more easily than Cloyster does, and in many cases it has more trouble switching in thanks to its inability to pose an offensive threat. However, when it comes to lasting long enough to both keep Spikes up and spin them away against slower teams, you can't do any better than Forretress.
So, the big thing Starmie lacks when compared to the other two is Spikes. However, it is the premier Rapid Spin user in the tier because of its access to Recover, which allows it to stick around longer than the most-used Spiker, Cloyster. In addition, it gets STAB Surf to check Ground-types, STAB Psychic to stop Machamp, massive Speed to cover threats such as Charizard and Nidoking while being able to smack Gengar and finish off low-health Zapdos who attempt to prevent it from spinning, and a movepool that includes Thunder Wave and Reflect for further team support outside of a limited spinning role.
However, as already mentioned, Starmie lacks Spikes, and despite its status in later generations it's not a very good attacker in GSC, so its offensive usefulness is limited strictly to a supporting role. Thus, Starmie is best suited for slower-paced teams. Even on these teams, though, Starmie is far less effective than other bulky Water-types such as Suicune when it comes to checking mixed sweepers and Ground-type attackers, so some synergy is still lost with Starmie even though it's a better team player than the Spikers are. Furthermore, in terms of the Spikes game it struggles to spin against Forretress and get past Misdreavus's spinblock, although with its STAB Surf threatening decent damage against Misdreavus it isn't impossible. It's also vulnerable to Pursuit because of its Psychic typing. All-in-all, Starmie is still the best Rapid Spin support money can buy, but Rapid Spin is never a sure thing.
Aside from the three metagame-defining options above, there are a few other somewhat effective Pokemon that can also use Spikes or Rapid Spin. Smeargle can set Spikes somewhat effectively, especially since it gets Spore to prevent spinners from switching in willy-nilly to spin them straight away. However, Smeargle often has more menacing things it would like to do, such as using Baton Pass to give an Agility boost to a sweeper, and its bulk is basically nonexistent, which means it's hardly good for a drawn-out Spikes war against a slower team.
As for unconventional spinners, there are Donphan and Tentacruel. Donphan is a Pokemon that was rather popular very early on in GSC, but has since fallen to mediocrity for various reasons, including disappointing special bulk and a lack of physical resistances outside of Rock. However, it spins against Raikou, Ghosts are afraid to switch in against it to block its spin, and it offers Roar support to make it perhaps the most defensively synergistic spinner in the game. Still, it is very mediocre as a spinner primarily because it invites Cloyster, the most common Spiker, to switch straight back in to reset Spikes and force Donphan right back out.
Finally, Tentacruel makes for a solid spinner. It beats both Cloyster and Forretress one-on-one, both short-term and long-term. It is immune to Cloyster's Toxic and does not take super effective damage from Forretress, making it more reliable than even Starmie at times. However, Tentacruel has next to zero team synergy, whereas Starmie at least offers niche defensive coverage and has support moves such as Reflect and Thunder Wave. In addition, Tentacruel struggles much more than Starmie does when trying to get past Ghost-types. Finally, Tentacruel misses out on Swords Dance when using Rapid Spin, and Tentacruel's Swords Dance set is widely considered its best set.
So now that you've bothered to read my blurbs on the main players in the GSC Spikes game, let's take a look at the Pokemon and strategies that lead to keeping Spikes on the field. It's usually necessary to pair a Spiker with at least one of these "assistants" if you want to be able to consistently have at least a chance at keeping them down. These assistants, how to use them, and what they pair best with are described below.
Obviously, the classic way to ensure Spikes stay down is to run a spinblocker. There are only two spinblockers available in GSC: Misdreavus and Gengar. Misdreavus has the benefit of lacking a Psychic weakness and having a little more Special Defense than Gengar, making it the more certain bet when it comes to blocking Rapid Spin, particularly from Starmie. For this reason, Misdreavus is the spinblocker that pairs best with Cloyster, as unlike Gengar, it can reliably block Starmie's spin. In addition, Misdreavus has the threat of Perish trap to force switches. However, Gengar is not without its selling points. It's immune to Toxic, so it doesn't require Heal Bell support to keep alive for a long period of time, and furthermore its attacking stats and movepool are better than Misdreavus's. Gengar is therefore a solid spinblocker to pair with Forretress, as Forretress can keep Spikes against Starmie while Gengar blocks spin against Cloyster and opposing Forretress.
It's important to note that Pursuit is a special attack in GSC. Pursuit users help to keep Spikes down against Starmie and Rapid Spin Cloyster. In addition, they can help your own spinners by taking out spinblockers and quickly taking out Cloyster, the most common Spiker. Tyranitar is by far the most common Pursuit user, and it is the best at sniping Ghost-types. However, its Water weakness leaves it vulnerable to a likely 2HKO from Starmie and a possible 2HKO from Cloyster, so it must tread carefully if it is going to attempt to Pursuit these threats. Generally, pairing Tyranitar with Light Screen support or Icy Wind from your own Cloyster gives it the advantage it needs to perform in these match-ups.
Alternatively, Umbreon is a much more reliable Pursuit user, but unfortunately it doesn't have the power needed to actually KO things with its Pursuit. It fails to snipe Misdreavus because it cannot do enough damage to outpace Perish trap, and Starmie, while seemingly easily beaten by Pursuit Umbreon, can actually stall it out of Pursuit PP by spamming Recover. However, Gengar and Cloyster are slowly but surely eroded by Pursuit Umbreon, and Starmie still faces an uphill battle in dealing with it.
Using status to mess with the Spikers and spinners makes it much easier to win the Spikes war. Toxic is usually the easiest status to use against Cloyster and Starmie, and is especially useful for limiting the lifespan of the former to prevent it from setting or spinning Spikes in the long run. Wearing down Starmie with Toxic is trickier, given its access to Recover, but it is possible since Starmie does not have Natural Cure in GSC. The idea is to repeatedly bait Starmie into switching into Cloyster and subsequently use Rapid Spin as you switch to a Pokemon such as DrumLax or Raikou to immediately force it to switch out before it can use Recover. Eventually, it will need to Recover instead of spinning, although getting to this point can be a chore. Usually, the best Pokemon to deliver Toxic against Starmie and Cloyster is your own Cloyster, although if Cloyster is your main target, other Pokemon such as Suicune, Skarmory, and Forretress are also good at baiting it into taking Toxic.
Of course, if Forretress is the spinner you need to beat, Toxic isn't going to do you any good. Fortunately, catching it with paralysis or even sleep is a good way to prevent it from using Rapid Spin or Spikes. Snorlax with Body Slam or Lovely Kiss is especially good at drawing in Forretress to inflict status on it, as is Exeggutor with Stun Spore or Sleep Powder. Miltank is also good at baiting Forretress and paralyzing it with Body Slam. Snorlax and Miltank are also good at drawing in Cloyster to take these statuses. Starmie is most reliably afflicted with status by Toxic, as it is usually cautious about switching into paralysis or sleep, although Body Slam Steelix or Machamp do a good job of paralyzing it, whereas Exeggutor and Nidoking can occasionally have opportunities to put Starmie to sleep. In general, though, it's a bad idea to rely on being able to inflict status on Starmie outside of poison, since Starmie tends to avoid status like the plague.
Using status to try to keep Spikes generally requires a lot of patience and extra support, and your hard work can always be undone by a Heal Bell user. If you encounter a user of Heal Bell, be sure to have a plan against it, whether you intend to capitalize offensively in response to its switch-in (e.g., switch a strong special attacker in on Miltank, a physical attacker in against Blissey), waste its 8 Heal Bell PP, or simply prevent it from switching in to begin with.
Aside from baiting Spikers and spinners into taking status, certain Pokemon are good at baiting them into taking big hits. Steelix often forces opponents to switch Water-types in against it, so it has a chance of baiting Starmie or Cloyster into taking that Explosion. Steelix should be able to survive Surf from both if at full health, so that Explosion need not necessarily be used on the switch. In addition, Icy Wind Cloyster can set Spikes as Starmie switches in and gain the Speed advantage by using Icy Wind as Starmie uses Rapid Spin. This can allow a slower Pursuit user such as Tyranitar an opportunity to switch in and have an advantage in a match-up where it otherwise loses because of its Speed. If Starmie is poisoned before being slowed by Icy Wind, Cloyster might eventually keep Spikes on Starmie by itself since Starmie must eventually use Recover instead of indefinitely spamming Rapid Spin, and when that happens Cloyster can outspeed and explode on Starmie before it can spin. Icy Wind Cloyster can also give itself the Speed advantage against other Cloyster switch-ins, which can be especially helpful when you need to explode on an opposing Cloyster to prevent it from spinning away your own Cloyster's Spikes.
Other Pokemon allow you to win Spikes wars by baiting these Spikers and spinners into taking hits without using Icy Wind or Explosion trickery. For getting past Starmie, Pokemon such as Marowak, Rhydon, Machamp, and sometimes Nidoking can goad Starmie into switching into powerful neutral or super effective hits. Cloyster can be goaded into taking big hits from Marowak and Rhydon, or can even be caught off-guard by an opposing Cloyster with Hidden Power Electric, which 2HKOes opposing Cloyster but does not do enough damage to be useful against Starmie. Beating Forretress can be done by concealing the presence of a Fire move, such as Fire Blast on Snorlax or Hidden Power Fire on Exeggutor, then letting loose when you think your opponent has let their guard down with Forretress. Not only is this strategy good for keeping Spikes against spinners, it is also good for beating the opponent's Spiker to make your own spinner's life easier. However, this kind of tactic often relies on surprise, and as a result it can fail to work if your opponent sees it coming.
Setting up Spikes and keeping them can be hard work. Now that you've managed to do it, though, you can now reap the rewards of what you have sown. Spikes on its own is rarely enough to flat-out KO anything, unlike the multiple layers available in later metagames where Sand Stream is available to help out and Rest is also far less prevalent. Thus, you cannot just splash Spikes haphazardly on a team and call that "offense." You must pair it with something else to make the most of these Spikes, and the following options are the best jelly available for Spikes' peanut butter.
Two status effects in particular, paralysis and poison, receive enough distribution to effectively capitalize on Spikes. Paralysis is often inflicted as a secondary effect of standard moves, such as Snorlax's Body Slam and Zapdos's Thunder. However, you can also use Stun Spore Exeggutor or a Thunder Wave user such as Starmie or even Porygon2 to effectively spread paralysis. Paralysis is great alongside Spikes because it not only forces opposing Pokemon to take Spikes damage on the switch-in, but their lowered Speed ensures that they take two turns' worth of damage upon switching in, even from the likes of Snorlax. This can seal the deal against faster Spikes-vulnerable foes such as Raikou, which, as the fastest viable RestTalk user in GSC OU, can otherwise be difficult to KO before it Rests. Paralysis also helps setup sweepers outspeed foes and get free turns of setup, so paralysis provides versatile, well-rounded offensive support outside of merely enabling opportunistic KOs.
Poison is almost exclusively inflicted with the move Toxic. Poison's main role alongside Spikes is to stack damage on the switch-in. Poison works a bit differently in GSC relative to other generations. Toxic poison reverts to normal poison after the affected Pokemon switches out. In addition, poison damage is assessed immediately after a Pokemon is willingly switched in or immediately after that Pokemon makes a move unless the poisoned Pokemon KOes the opposing Pokemon. Thus, a poisoned Pokemon switching in on Spikes, even one poisoned by Toxic, will take 25% damage from that alone (12.5% from the poison and 12.5% from the Spikes), making it much easier to force this Pokemon to Rest or even to KO it if the Pokemon is slow.
It is important to note that, because of the timing of poison damage, if a phazing move is used, the Pokemon that was willingly switched in takes poison damage on top of Spikes damage immediately before being phazed out, although a poisoned Pokemon that is forcibly switched in by Roar or Whirlwind will not have the poison damage assessed until the following turn. This combination is particularly great for wearing down Snorlax, which is often the Pokemon that poses the biggest threat and which usually houses slower opposing teams' win condition. However, Toxic is a lot less versatile than paralysis, as fast RestTalk users, such as Raikou and Zapdos, do not care about poison at all and setup sweepers are not helped very much by poison support. Still, Toxic gets much better distribution than paralysis moves do, so poison support can be preferable for teams with a lot of walls, such as Suicune and Umbreon, which otherwise have no other means by which to impose offensive pressure.
One thing to remember when using status is to ensure that it gets spread widely. This means using a host of paralysis or poison inducers that can force a wide variety of Pokemon into taking the status move of your choice. A detailed description of this is topic enough for another article entirely, but essentially, you want to use Pokemon that bait your status targets into switching in (e.g., Body Slam Steelix baits Suicune into taking paralysis, Toxic Cloyster baits Starmie into taking Toxic). In addition, Pokemon that avoid targeting Pokemon who normally don't care about your status of choice—for example, sleeping RestTalk users and CurseLax for paralysis-based teams; Steel- and Poison-types and RestTalk-using Electrics for poison-based teams—make for the best status supporters. If nothing else, make sure that paralysis-based teams can target Raikou and that Toxic-based teams can target Snorlax, for these are the most relevant threats to target with status as mentioned above.
It should be obvious that attacks do damage, and hence are good for any offense to have. However, what do I mean by having "opportunistic" attackers that can take advantage of Spikes? Well, really, what I mean by this is that attackers that can do a lot of damage without having to set up benefit the most from Spikes. Pokemon such as Vaporeon, Charizard, and Quagsire that rely on setting up to destroy their foes can still be paired with Spikes; there is nothing wrong with that, as Spikes can be useful in wearing down their most prominent counters. However, to utilize Spikes to their fullest, it is best to use offensive Pokemon that do not require setup. Mixed sweepers such as Nidoking, Tyranitar, and Dragonite greatly appreciate the fact that Spikes can enable them to take out their most prominent counters, Suicune and Raikou. Zapdos and Raikou with Thunder do appreciable damage to Snorlax, but nonetheless fail to 3HKO it, meaning that they get Rest-looped under normal circumstances. Spikes forces Snorlax to take that extra bit of damage on the switch in to make the KO by STAB Thunder much more likely. Snorlax itself is a big offensive threat with or without setup and loves Spikes support to help it wear down foes such as Misdreavus, Tyranitar, Steelix, and Miltank. Marowak, Machamp, and Rhydon are also deeply appreciative of Spikes support, as it makes life much easier for them when they have to get past Suicune and Exeggutor. There are other attackers, such as Exeggutor and Gengar, that appreciate Spikes's ability to wear away at Snorlax and Raikou.
Pokemon with phazing moves literally force switches, and with prediction they can shut down the opponent's offense, force Pokemon to accumulate Spikes damage and be forced to Rest without accomplishing much in return, and in certain cases, can force a Pokemon such as a low-health Snorlax to switch in on Spikes and sentence itself to death before it can find an opportune time to Rest. Raikou is far and away the best phazer to pair with Spikes. Its STAB Thunder prevents Spikes-immune foes such as Zapdos and Skarmory from staying in, and additionally doesn't allow Rapid Spin users to blow away Spikes. Furthermore, while most teams have at least two good switch-ins to Raikou, the other four Pokemon on many of these teams will likely be Pokemon such as Suicune and Skarmory and consequently will match up quite poorly against it. Thus, Raikou can force a long-lasting cycle of one of its counters switching in, taking Spikes damage, then being Roared out to bring in another favorable match-up for Raikou.
Steelix is another decent phazer to pair with Spikes, as it can repeatedly Roar out counters such as Suicune and Miltank that are pressured to switch in and take Spikes damage by Steelix's ability to set up Curses against common opponents such as Snorlax (especially mono-Normal variants) and Raikou. However, Steelix does not do a good job of preventing Rapid Spin and needs Rock Slide to stop Spikes-immune Flying-types from staying in, so it needs a little more support to be effective. Tyranitar is also a pretty good Spikes shuffler, but unfortunately four-moveslot syndrome prevents it from getting all the favorable match-ups it would like, and in general would rather be using Pursuit against the Flying-types it forces out instead of trying to Roar shuffle the opponent's team.
Other phazers such as Suicune and Skarmory aren't exactly the best phazers to shuffle the opponent's team to rack up Spikes damage, most notably because they let Zapdos and spinners have their way with them. Regardless, they both have limited offensive prowess, and it's not as though their ability to Roar shuffle is totally ineffective, so if Skarmory or Suicune must be active, you might as well try to Roar shuffle. Perish trappers such as Misdreavus and Gengar can also effectively phaze opponents, forcing foes to go immediately to their own phazers. If enough Spikes damage can be racked up on these phazers as they switch in, they can be forced to Rest, which gives these Perish trappers an opportunity to capitalize on the situation.
Spikes should be utilized if you are using a fairly slow team and expect stall endgames to arise frequently. Spikes tend to put powerful offensive Pokemon without Rest, such as Marowak and Nidoking, on a timer, thereby allowing a team with a lot of passive members to legitimately outlast an offensive one instead of simply waiting to lose. It also does a good job of making life much more difficult for DrumLax attempting to set up against or get a Rest in against your stall. Furthermore, once you get to the stall endgame where neither player can outright break the other, Spikes helps to prevent the opponent from simply endlessly switching, thereby allowing you to eventually win the PP war. However, if you want to be sure to win stall endgames, you ought to use a Rapid Spin user, as Spikes alone does not confer an advantage. You need to also lack Spikes on your own side so that you can conserve your own PP by switching without consequence. Preferably, this spinner is not Cloyster, as Cloyster is on a much shorter timer than the Toxic-immune Forretress and the Recover-using Starmie are. Using a spinblocker is also all but mandatory, because you really need to be able to ensure Spikes are down if your passive team is going to be able to force a stall endgame instead of slowly withering away. Generally, the Pokemon that work well to force a stall endgame are those often seen on a team that pairs Toxic with Spikes; Pokemon such as Suicune, Umbreon, and Skarmory are impeccable stallers. Of course, you will need to use Pokemon such as Snorlax and Raikou and double-switch to them frequently to place enough offensive pressure on an opponent that adopts a similarly defensive playstyle, lest many of your matches simply end in a tie.
Of course, now that you know about the best ways to use Spikes and the reasoning behind them, you might be scheming your own teams and, possibly, even your own devious Spikes strategies. Before you get too far, though, remember to avoid the following common pitfalls when using Spikes.
I cannot stress this enough. It's generally a mistake made by newer-gen players farting around in GSC, so advanced players looking for nuance from this guide don't need to worry about this too much. However, I'd rather not see even the beginners waste precious turns by trying to set up extra layers that don't exist in GSC. So, to reiterate: there is only one layer of Spikes in GSC. There is only one layer of Spikes in GSC. There is only one layer of Spikes in GSC. Don't waste your time trying to set up more. Furthermore, because there's only one layer, learn to work with just that one layer. Spikes's advantage, as I've said before, is a lot more nuanced in GSC than in future generations where multiple layers of Spikes are shaving off a quarter of foes' HP and many more foes cannot recover HP.
This has also been touched on before, but do not be too passive with your teams just because "you have Spikes" for offense. Even if you're using a slower team with passive Pokemon such as Suicune and Skarmory, you should have some hefty offensive threats such as DrumLax to double-switch to frequently to keep the pressure on, and ideally some other offensive pathways such as capitalizing on Spikes with a phazer, having a Perish trapper to take advantage of an opponent's downtime, or having a mixed sweeper to go to for outright damage when Snorlax is asleep. Otherwise, Spikes alone probably will not be enough to pressure offensive teams into switching around and fading away, and you'll end up in deadlock against similarly defensive teams. Spikes is only one aspect of the game, and the Spikes advantage is not a win condition in itself unless you're looking at a stall endgame with 2-3 Pokemon per side.
I should preface this by saying: if you have an offensive team with a lot of attacking moves and Explosion users, you can afford to just splash a Spiker on your team, as the option to set up Spikes is always better than not having it at all. Generally, the splashable Spiker is Cloyster because it provides immediate offensive pressure with Explosion and some defensive synergy against Ground-types, so the team gives up little while gaining Spikes. Furthermore, with a hyper-offensive team that makes use of a strategy such as JoltWak to end the game quickly, you don't need to worry about Spikes at all. However, if you want to utilize Spikes + Roar, are using a slower team that doesn't have all that many attacking moves, or in general want to make Spikes a focal point of a reliable offensive attack, you can't just splash a Cloyster on your team and expect things to go hunky-dory. You'll need to run support to make sure you can keep Spikes. Maybe this is direct support in the form of spinblock. Maybe it's more situational support such as Pursuit or Toxic paired with a RestTalk-using Electric-type. Regardless, you need to think about not only using a Spiker, but also how you'll keep Spikes up if Spikes plays a central role in the success of your team.
This can catch you by surprise if you start focusing too much on the Spikes metagame, particularly if you are using a spinner. Your instinct is usually to either save your Spiker until you can keep Spikes against a spinner or to repeatedly switch your spinner into the opposing Spiker. Don't get caught in the trap of saving Cloyster when exploding it would open up a Belly Drum Charizard or Machamp sweep, or switching your Starmie into Cloyster repeatedly for DrumLax or Electric-types to take advantage of it. Remember that Spikes, while very useful, is only one part of the game, and that you sometimes need to forget about Spikes and see the situation as a whole to come out with the win.
Of course, I've been singing the praises of Spikes and the strategies that capitalize on their presence. I've tried to be realistic about their nuanced effectiveness, although I recognize that I have stated that GSC is the best generation for Spikes, if for no other reason than because other forms of passive damage are hard to come by. However, Spikes has definite limitations that you must account for when using them.
Zapdos is probably the biggest pain in the ass for a team looking to abuse Spikes, hence why its name in the header for this paragraph is in ALL CAPS. Specifically, Zapdos is immune to Spikes, is a huge offensive threat, and can tank hits from most unboosted attacks, even super effective ones. Zapdos is a big reason why Raikou and Steelix are good phazers to pair with Spikes; they're not forced out by the standard Hidden Power Ice Zapdos, and generally are able to hit it pretty hard in return. Still, they're not full stops to Zapdos. Zapdos can afford to take a couple hits from these Pokemon, and can paralyze Raikou with its Thunder while chipping away at Steelix with Hidden Power Ice. Furthermore, Zapdos cuts the effectiveness of Spikes + Roar in half, as normally Spikes + Roar forces two Pokemon to take Spikes damage, whereas Zapdos's immunity ensures that, if it switches in, only one Pokemon has to. Zapdos is also a good reason why Tyranitar is such a good mixed attacker for utilizing Spikes. While Tyranitar has much more severe four-moveslot syndrome than Nidoking or Dragonite, it has access to a STAB Rock Slide, which achieves the rare feat of 2HKOing Zapdos. Furthermore, it has Pursuit to chip away at Zapdos even as it switches out. However, Tyranitar cannot afford to switch in on Zapdos's Thunder, which 3HKOes it.
Really, Zapdos can be a pretty problematic foe to go up against for any kind of team, but it's especially frustrating for a Spikes-based offense. Just be sure you have plenty of plans for dealing with it. Raikou, Tyranitar, Light Screen Blissey, Snorlax, Quagsire, and Pokemon that can explode on it—such as Exeggutor and Gengar—are all good things for dealing with Zapdos, and having many answers to Zapdos is vital because Zapdos can generally match up very well against even its "counters."
On the other hand, Skarmory can make use of its own Flying typing to avoid Spikes damage and be difficult to break when walling Snorlax. However, Skarmory doesn't impose offensive pressure the way Zapdos does, so it's easier to switch into. Just be careful to use Pokemon that both make the most of Spikes and can deal with Skarmory and you should be fine. This should be easy, since most of the more prominent Pokemon that pair best with Spikes can force Skarmory out pretty easily, but if you're not careful you could end up being dependent on a core of, say, Giga Drain Exeggutor and Earthquake CurseLax to capitalize off of Spikes, which would make life against Skarmory needlessly difficult.
The big problem with the Spikers and spinners is that they sacrifice some of the other team synergy you might otherwise have in that slot. Cloyster's defensive utility is limited to checking Marowak, Rhydon, and Steelix, and its offensive utility is limited to Explosion. Forretress offers nothing except a secondary check to Exeggutor. Starmie offers the most synergy, but takes a lot of damage in return from most of the Ground-types it checks, its other defensive roles such as countering Machamp and Charizard are frequently unneeded, and it's generally an easy switch in for offensive threats such as Snorlax and Raikou. Teams that use Spikes are often forced to also run a spinblocker to ensure that Spikes stay down, which leaves only four Pokemon slots to establish offensive and defensive synergy outside of Spikes. On many teams, a balance must be struck between having enough support for Spikes and having enough room for Pokemon to capitalize on them and other vital teammates.
Spikes are likely at their most important in GSC because of the lack of other truly good options for passive damage. However, they're not necessarily as effective as they are in later generations, because in GSC, everything can recover HP and you only get one layer. Spikes are very helpful for getting opportunistic KOs with Pokemon that attack well without needing setup, and are also necessary for slower teams that do not use many attacking moves. However, it is important to realize that Spikes are limited on their own, and that plenty of support, both in keeping Spikes on the field and utilizing Spikes, is necessary to get the most out of them. It's also important to remember that Spikes are not the end-all-be-all of GSC; while important, they are only one aspect of the game. Despite Spikes being the focus of this article, be careful to look at situations holistically and to put Spikes on the back burner if you are becoming predictable with your spinner switch-ins or if you see a way to pressure the opponent offensively without Spikes.