DTC:
Azelf: BAN
Unlike Sableye, it's hard to pinpoint that one really broken set on Azelf because it's such a versatile Pokemon. A Nasty Plot set OHKOs almost the entire tier once set up, and while it's frail, Azelf forces a lot of switches. Unlike many other setup sweepers, Azelf is more than capable of being effective before a boost, thanks to its 125 base Special Attack, amazing coverage, and 115 base Speed. Azelf has such an expansive movepool consisting of coverage moves such as Fire Blast / Shadow Ball / Thunderbolt / Knock Off / Grass Knot, as well as an excellent 125 base Attack stat, that makes it hard to counterplay because it's hard to tell what moves it is running. A simple set of Nasty Plot / Psychic / Fire Blast / Shadow Ball is almost impossible to counter as is, but when you add a bunch of other moves to the table, and the fact that it outspeeds almost the entire unboosted tier, Azelf becomes that much more ridiculous.
Tsunami:
Azelf: BAN
Azelf can run a wide variety of sets ranging from Mixed to a Stealth Rock suicide lead. The suicide lead set can use Explosion to severely cripple the opposition, and getting up Stealth Rock with it is rather easy due to the great deal of switches Azelf usually forces. This aforementioned ability to force switches also makes it incredibly easy to set up a Nasty Plot. A +2 Azelf can OHKO most of the tier thanks to its superb coverage moves. 115 Base Speed ensures that Azelf won't be outrun by too many non-Scarfed threats, making it even more deadly. The aforementioned Mix set can also cause major problems for teams, and cripple them for the remainder of the game with Knock Off. Azelf's Psychic-typing also makes it resistant to Fighting-type moves, which are some of the most common priority attacks in the metagame, making it even more difficult to take out. It also has access to a Dual Screens set, which, while rarely seen, can be a force to be reckoned with on a SmashPass team. Azelf's versatility, raw power, great Speed, and ridiculous coverage make it too large of a threat to be dealt with properly in the RU metagame.
Hotncold:
Azelf: Ban
Well, I had a lot of doubts with Azelf at first thoughts because is just frail and weak to dark/ghost bluff but still is a extremely versatile pokemon with a lot of options: Nasty Plot, Choice Band, Suicide lead, Screens supporter, Mixed atacker or Utility with Stealth Rock + 3 atk; is just too unpredictable with the right moveset beats almost every threat in this tier - best way to handle this is with another offensive presence in the same level power something this tier lacks, Azelf with that speed base outrun every relevant threat in the tier except Sceptile and Dugtrio, not mention here Scarf mons which obviously have drawbacks using their choice item. Azelf is kinda the typical pokemon which dont need even a decent bulk, just with their offense presence is usually enough.
Molk:
Azelf: ban
Too much power, too much speed, too many options. Azelf comes packed with absolutely amazing dual base 125 mixed offenses as well as a movepool with not just good tools such as U-turn, Stealth Rock, Dual Screens, Explosion and Knock Off, but any coverage move it'll ever need, getting moves such as Energy Ball, Shadow Ball, Psyshock, Thunderbolt, Fire Blast, and more to run through the opposition, and even a great boosting move in Nasty Plot that lets it run right through defensive teams with ease and OHKO almost the entire tier after a boost, combine this with an amazing Speed stat of 115 that outruns pretty much the whole unboosted tier outside of say Sceptile, and you have quite a monster on your hands. In the end, i think this combination of power, speed, support options, and versatility is simply too much for the current RU tier to handle, and therefore Azelf should be banned.
Nails:
Azelf: No Ban, I expect it to be broken and I wouldn't be shocked if it's quickbanned but unlike the other two I don't think its power level is high enough to warrant a quickban. It's pretty easy to revenge kill, it has no bulk or recovery and I feel it's dealt with on paper at least by most tanky mons. I think mixed sets are pretty terrible, I don't think explosion is very strong since dpp, and Nasty Plot is pretty simple to revenge kill. I'm like 75/25 ban/no ban on Azelf but I think quickbans should be more certain than that. I might edit this to ban later though if I'm allowed to since it's rly close. But I could see a scenario post Sableye/Kyurem where it's not broked, which is enough atm.
Spirit:
Azelf: Abstain
This was the one I had the most difficulty deciding upon. On one hand, its stats and movepool make it an offensive behemoth; on the other hand, its general frailty, poor defensive synergy, and thus its lack of switch-in opportunities makes it difficult to utilize these traits to the fullest. The two sets that I think are worth discussing is the mixed set and the Nasty Plot set. I don't find the support sets to be all that game-breaking, setting up Stealth Rock and then Exploding or setting up dual screens and doing the latter isn't always going to be the precursor towards deciding a match. In terms of its influence on offensive teams (where all-out attacker sets are generally more effective), again, the frailty allows it to be taken out by moderately strong priority (Sucker Punch being the most common in this tier) whereas there are Pokemon--even on offense--that are capable of taking a hit and doing some serious damage back, such as Raikou and Druddigon. The Nasty Plot set finds most of its use against stall / slower teams, where admittedly, it's very destructive. There aren't that many full stall teams on the ladder though, most are semi-stall that have something that can revenge Azelf / force it out and thus keep it from sweeping their team. I just haven't faced very many stall teams on the ladder and even then, I didn't get much of a chance to really see Azelf's impact on them. As for slow, bulky offensive teams, trying to set up is pretty difficult without something like Memento Dugtrio support, and here's the thing that really annoys me with Azelf: if it can't KO the current target it's up against, it'll likely find itself the one taken out instead. I'm not denying that this Pokemon is potentially broken because with Sableye leaving (thus losing one more check) it's a definite outcome, but at this point, I can't say that it's quick-ban worthy nor can I confidently say that it's just fine.
atomicllamas:
Azelf: Ban
Azelf is blessed with what is quite possibly the best offensive move pool in all of Pokemon (barring mew), and has base 125 offenses, and a base 115 speed to back this move pool up. Due to its offensive versatility, it is pretty much uncounterable in RU, and unless you have god-like prediction skills, you will be sacking at least one Pokemon to Azelf. Between Choice Band, Choice Specs, Choice Scarf, Nasty Plot, Suicide Lead, and an Offensive Dual Screens set, Azelf is capable of luring in and disposing of whatever Pokemon a teammate needs removed or weakened, in order to sweep, or efficiently sweeping by itself. Most of the arguments for the retention of Azelf in RU (that I have seen), like to point to its "frailty" as a reason that Azelf is not to much for the tier, but all of these "checks" are unable to switch into Azelf, meaning Azelf has already killed a Pokemon on your team. I'd also like to point out that 75 / 70 / 70 bulk isn't even that bad, and can easily set up on defensive mons without a SE STAB move, its bulk is comparable to Toxicroak's and even Sableye's, which while it is nothing to write home about, isn't necessarily bad. All in all, Azelf's stats and move pool create an extremely versatile Pokemon, that pretty much always puts the Azelf user in an advantageous position due to the mind games it creates for the opponent (especially with U-turn vs Nasty Plot factored in).
Silentverse:
Azelf: Ban
This is a dumb. Imagine if Magic Guard-less Alakazam was RU, except if it had Nasty Plot, way better coverage moves, an immunity to Spikes and Toxic Spikes, and the ability to go mixed with strong coverage in U-turn and Knock Off. Ok, that's not really like Alakazam at all, but you get the gist of what I am trying to say (I hope). Essentially, Azelf is an extremely fast and diverse threat whose different sets each has a very limited set of counters, and due to how strong it is, guessing wrong is just so punishing for the player who has the misfortune of having to deal with this thing. After a Nasty Plot, Azelf literally OHKOes virtually everything in the tier, and its Speed is fast enough to make revenge killing a chore, especially as right now, RU lacks a lot of good scarfers, and the few Pokemon that can take a hit after a Nasty Plot (Assault Vest Slowking, specially defensive Spiritomb and Skuntank I guess?) get worn down by CB / LO Knock Offs / U-turns very quickly, making them shaky initial switch-ins. Playing against Azelf is a guessing game that is almost always in the favor of the person using the Azelf, and for this reason, Azelf needs to be quickbanned.