When initially evaluated prior to the Azumarill suspect, we decided that Blaziken was fine, based mostly on the Normalium set that was popular at the time, due to the fact it suffered from similar issues to what it faced in NatDex OU - while it may take out one check, the second check (which would often be on a team regardless of Blaziken) would still stifle it entirely, meaning it often blew its usually only chance to sweep due to its poor bulk. However, it has recently, over the course of the recent Alakazam suspect test, begun to rapidly prove itself too much for the meta - we have generally come to realise that Rockium is considerably more effective in the current metagame than the Normalium set, due to the fact that Stone Edge even without Continental Crush is still able to get past a significant number of its checks, such as Moltres and Salamence after Intimidate, without worry of recoil, meaning that often the second check will be taken out by a boosted Stone Edge anyways. And as a significant number of our Blaziken checks are rock weak, teams are often left vulnerable to just being run through by Blaziken thanks to its powerful STABs, solid STAB combination, high offensive stats, access to Swords Dance, and Speed Boost, at worst often taking two mons with it as teams attempt to force it to KO itself with Flare Blitz recoil and Rocky Helmet mons. Teams may be forced into uncomfortable prediction games to dodge the Continental Crush with their non rock weak check that the Blaziken will generally have the advantage in.
It isn't like Blaziken is unbeatable, of course, but the list of checks are simply far too small for our liking, with all but two of its few defensive checks consisting of niche sets (like PhysDef Swampert and Hippowdon, both mons that vastly prefer their SpDef sets in most other cases) or mons, or have no reliable recovery (again, PhysDef Swampert), while its offensive checks list, other than extremely risky doubles on the Swords Dance with a base 80+ scarfer, consists of Aqua Jet Choice Band Urshifu and Azumarill. Additionally, Hippowdon, Mega Altaria and Swampert are often tasked with checking a lot of Pokemon (the grounds additionally finding this harder due to not being the generally optimal SpDef set), and are often Toxic magnets, meaning they get worn down quickly and blown through by a +2 Blaziken as a result. Defensive Mega Altaria sets, the only set that can actually take +2 Continental Crush, also struggle to actually deal with Blaziken, failing to actually kill and at best can fish for a Body Slam paralysis, which Speed Boost can negate the speed drop of eventually anyways. Meanwhile, Mega Altaria doesn't need much more chip than just pre mega Stealth Rock or two rounds of post mega Stealth Rock chip to be put in range of +2 Continental Crush, which it will often accrue - rocks or no rocks - due to how much it is needed to check and its lack of passive recovery.
This means that, realistically, PhysDef Slowking and Gligar are the only good and reliable defensive checks that aren't quite niche otherwise, the former potentially being forced to sacrifice several of its teammates to Regen up to high enough to take Continental Crush (especially by Pursuit), leaving the Blaziken user at a distinct advantage, and the latter, while good, is nowhere near splashable enough to balance Blaziken, and will be forced to take a massive amount of damage from +2 Flare Blitz if Blaziken is full HP due to the fact Earthquake never OHKOs Blaziken. Additionally, if Gligar loses its Eviolite via Knock Off, it has a good chance to be KOd by Flare Blitz after Stealth Rock, which will also wear it down faster in general due to it being unable to run Heavy-Duty Boots or Leftovers.
While Blaziken can struggle to set up at times, there are still a significant number of common Pokemon it sets up on more or less for free, namely Amoonguss, Sludge Bomb poisons notwithstanding, Skarmory (due to the fact that Brave Bird is nonexistent due to the fact that Skarmory needs Body Press to deal with Melmetal, one of the main things it is used to check), Celesteela, Scizor, non Taunt/boosted BU Dark Z Zarude, and Bisharp. Additionally, it can often force switches relatively easily vs the likes of Melmetal and Tangrowth, giving it even more opportunities to set up.
Overall, given its ability to simply win with too few options to stop it, and its tendency to take at least two Pokemon with it even if it can be stopped, we have decided to quickban Blaziken from the tier.
Tagging Kris to implement, thanks in advance!