team talk
I've been having fun with a Ghost team, and there's a number of interesting aspects to talk about -for instance, I've counter-intuitively struggled most consistently with Fairy and Steel type Pokemon/teams, rather than Dark or Ghost- but one of the biggest, most relevant things is...
Mega Lopunny
On every level Mega Lopunny has been hugely influential on how I've constructed my team, more so than any single other Pokemon in the meta.
As an enemy
It's tempting to make your Physical walls Dark/Ghost and/or Steel/Ghost. Mandibuzz and Skarmory are amazing Physical walls that are both a great stop to most every unboosted Physical attacker to be found, and they even make for a good pair, as Mandibuzz's only weakness is Fairy, which Skarmory resists. Mandibuzz can actually shrug off most Knock Offs, often able to Roost right through them, even powerful STAB Knock Offs, making it a very tempting wall for a Ghost team. However, if your Physical walls are
only of these types, you're at significant risk of being 6-0ed by Mega Lopunny. It doesn't even need to run High Jump Kick to 2HKO them!
This isn't a niche consideration, either, as Mega Lopunny can be slapped into literally any team regardless of added type and retain full functionality, and I'd argue only Dark and
maybe Fighting teams consider Mega Lopunny unappealing. Other teams might overall prefer different Megas, but it's not as if Mega Lopunny actually suffers from being attached to a Steel or Dragon team.
It is of course immune to your default team STAB of Ghost. Normally Normal types are actually pretty unthreatening to a Ghost team, because they can't touch your Ghosts with their most powerful attacks (Boomburst, Frustration, Facade, etc) while Ghost attacks cap out at 80 BP anyway so mutual STAB immunity overall favors the Ghosts, but Mega Lopunny is very much an exception and is, in fact, completely impossible to resist both its STABs, particularly in a Ghost team, which can't even get a hold of the likes of unmodified Skarmory. (Which resists Normal while being neutral to Fighting, and thus fairly effectively walls Mega Lopunny that are running Drain Punch over High Jump Kick)
It also is so fast that it can easily outspeed most non-Scarfed Pokemon, making it difficult to even revenge it. Gengar's your team leader? Yeah, too slow, OHKOed by Return/Frustration.
As Mega Lopunny exists, a Ghost team
needs to have Physical walls that are reliant on strong neutral bulk rather than favorable typing to successfully tank Mega Lopunny -Hippowdon, Slowbro, and Tangrowth are some of the better possibilities. Mega Altaria is also worth noting, particularly as it combines well with a Ghost team in general -once Mega Evolved, it resists the ever-problematic Dark type, and Fairy offense is of course great for threatening otherwise-tricky Dark teams.
Second place goes to Pangoro, which is a Scrappy Fighting type no matter what team goes on it while not consuming the Mega slot (And having impressive Attack, just below Mega Lopunny's but with the potential to bolster it with Life Orb or Choice Band and actually pull ahead), and third place goes to Kangaskhan, Miltank, and Stoutland, all of which have some potential on, if nothing else, Fighting teams, again as a Scrappy Fighting attacker that does not consume a Mega slot. Keep in mind whether your Mega Lopunny check is an adequate check to the likes of these, as well, or make sure other Pokemon on your team can fulfill the role.
As an ally
Somewhat surprisingly, Mega Lopunny is a fantastic
ally to Ghost teams. The two types a Ghost team most consistently struggles with are of course Ghost and Dark, and Mega Lopunny is immune to the first and resistant to the second, making it surprisingly competent at switching in safely into opponents that threaten the entire rest of your team. Meanwhile it brings powerful STAB Fighting that
cannot be ignored to bear against opposing Ghost/Normals and Ghost/Darks that may otherwise suck momentum from you, has a fantastic utility movepool that it honestly might as well run
something from since its coverage isn't very useful in Type Reflectors (Ice Punch is actually 2 BP
weaker than Return/Frustration against something like a Dragon type, thanks to the hidden 2 extra BP on every move), and if you're running Drain Punch it's shocking how often it can switch in, soak a hit, and come back to do it again later, having fully healed itself with a Drain Punch.
Only Mega Gyarados, Mega Altaria, and Mega Audino provide a similar capacity to consistently resist and threaten anti-Ghost threats, and I'd argue none of them does the job as well as Mega Lopunny. Mega Gyarados is resistant to both relevant types (Slightly worse than being immune to one and resistant to the other), but in spite of its superior bulk it actually has worse longevity, having no way to heal itself, and it doesn't actually have a STAB super effective move for Dark types, allowing individual Dark Pokemon to consistently, safely switch into it. Mega Audino is just kind of depressing in Singles in general, while Mega Altaria has no actual advantage against opposing Ghost types.
The most obvious benefits are dramatically improving your Ghost teams matchup against opposing Dark and Ghost teams -without turning to a Mega (Specifically, Mega Altaria or Mega Pinsir), literally everything on a Dark team will be, at best, neutral to Fighting, essentially requiring them to turn to Pokemon like Weezing if they want a Physical wall able to switch into Mega Lopunny. Ghost teams often fall prey to expecting Dark/Ghost and Steel/Ghost walls to be adequate for their Physical needs, to the point that Mega Lopunny can 6-0 some of the ladder's Ghost teams all by itself, and Normal/Ghost is, unsurprisingly, a common find on Ghost teams, one that Mega Lopunny also rips apart.
While Normal teams aren't a huge threat to your Ghost team anyway, Mega Lopunny is still able to 6-0 a lot of them, especially since Normal teams are especially guilty of relying on a Ghost to protect them from Fighting and leaving it at that. Theoretically STAB Extreme Speed should be a problem, but...
252+ Atk Choice Band Dragonite (Normal type) Extreme Speed vs. 0 HP / 4 Def Mega Lopunny: 231-273 (85.2 - 100.7%) -- 6.3% chance to OHKO
... yes,
Adamant Normal type Choice Band Dragonite only has a 6.3% chance of getting a OHKO with Extreme Speed. You'll
crit more often than you'll get a high enough regular damage roll. This is the strongest possible first-turn Extreme Speed in Type Reflectors, note, as only Ubers exceed Dragonite in Attack.
However, Mega Lopunny is also a big improvement to your matchup against Steel teams, particularly the ones foolish enough to rely solely on a Ghost for their anti-Fighting needs, and in general brings a lot of utility in Fake Out and so on. In general, Fighting is an amazing attacking type, and with Scrappy the obvious Ghost/type-weak-to-Fighting combinations don't even slow you down.
If you're a Ghost team, Mega Lopunny is huge, all around. Use it, fear it.