LMAO. In the Tera-Meta Hoopa-U is disgusting because of Choice+Tera Sets, specially the Physical one, Hoopa-U only need Tera Dark and spam HSFury or Knock Off, you may think why not use Bax since it's faster and stronger, well Bax strongest move has an immunity and can't bypass protects or subs, you can't stall or defend from Hoopa, it's one of the few mons who just needs 4 attacks alone to wreck the meta, hell Hoopa-U is one of the few natural KnockOff users so you don't even need to spam HSFury so get some progress since they do pretty much the same damage if the opponent has an item while taking away said item. I been using Hoopa-U in NatDex to great success and that meta has twice(three maybe if you count form changes) the threats and three times the gimmicks, hell even the special sets are borederline stupid, put it on PsySpam teams and kill everything with either boosted HSHoles or go TeraDark and spam Dark Pulse. Also people are calling it frail like REALLLY?? Sure it can't take physical hits but on the special side on other hand can tank some heavy stuff.
Bax having an immunity to block its strongest stab isn't a huge problem when you remember we have almost no bulky fairies at all. It doesn't have an entirely enjoyable defensive typing but it still has entry points against common Pokemon like RotomW or other bulky waters while HoopaU is both slow and defensively lacking which means getting it into battle against anything that isn't a super fat team is rough. You talk high praise of HoopaU in natdex but there's a reason it isn't even ranked there. It is bowled over by any fast pokemon (hell anything over 81 speed clocks it), and we have no shortage of those. The omnipresence of hazards also makes revenging it crazy easy as it will get chipped constantly. You can't run scarf because the speed is way too low to be helpful. Specs/band is still prediction reliant against a decently put together team, and the lack of defensive utility is awful. And this tier has no shortage of ways to abuse it (tera screws it over just as much as it powers it, because a timely tera to tank a hit and KO back)