I haven't played competitive mons in several years, but I decided to give SV a try. I have not been disappointed. This metagame feels especially fresh (and a little chaotic) compared to the last couple generations. I would give most of the credit for that to the fact that the viable Pokemon are an even mix of new releases and some old staples. The new releases (especially some of the Paradox Pokemon) are also some of the most extreme examples of power creep Pokemon has ever seen, leading to an extremely offensive metagame for the most part. I do think its reasonable to expect the meta to slow down as time goes on and some of the most blatantly broken Pokemon get banned. Terastallization is also a pretty fun mechanic to abuse, but I do ultimately think it should be removed from OU (more on this further down). With that all said, here are some of my thoughts on some of the Pokemon in the metagame as it stands now.
With the first two already banned and the second two clearly on their way out, I can say without a doubt that these four all deserve their bans. Flutter Mane was way too fast and strong, especially with its excellent STAB coverage. Last Respects is a broken move, and I think it's pretty clear the tier leaders want to ban the move instead of Houndstone when Home comes out (which I agree with). Palafin is just too strong not to abuse with a 60 BP STAB priority move coming off an insanely easy to achieve 160 Attack. Band will always have a place against offense, but Taunt + BU pushed it over the edge. Iron Bundle gets perfect STAB neutral coverage coming off great Special Attack, excellent Speed, and a number of boosting options with BE and/or Agility. I personally prefer HDB with Taunt because of how well it dismantles fatter teams while still not being a slouch against offense.
(Shed Tail)
I don't think it makes a whole lot of sense to allow Shed Tail in a tier where Baton Pass is banned. Cyclizar is clearly the the better abuser of it (it can even pass speed boosts after Rapid Spinning), but the amount of cheese this move could facilitate is too much, especially once the meta starts to slow down. While I'd prefer a Shed Tail ban, I don't think the meta will suffer a great loss if Cyclizar just goes instead. I do ultimately think a ban of some kind is inevitable, be it now or in the next couple months.
While Chien-Pao doesn't feel like that much of a problem right now, it's about to lose two checks in Palafin and Iron Bundle. Once these two are gone, the biggest things holding it back are its weak STABs and vulnerability to hazards. However, since its reasonable to expect the meta to slow down, I think it could become more of a problem down the line.
I know people are trending on Scarf Chi-Yu right now, but Specs is the straight-up fish devil walking out of the sea to roast every Pokemon in existence. Toxapex has to be at full to even hope to check Chi-Yu and even then, its not doing much of anything back to it, and Blissey has to be above 75% or so for Overheat. Very few offensive Pokemon can switch into even resisted hits more than once, and any type of check runs the risk of being surprised by Tera Water/Grass. 100 base Speed is really damn good on a wall breaker with this much raw power. The popularity of Gholdengo is also huge boon, since Chi-Yu can switch into its STABs pretty reliably. Much like Chien-Pao, I think this Pokemon deserves at the very least a suspect down the line if not sooner.
Speaking of Gholdengo, the cheese stick man offers a stunning amount of role compression in blocking both Rapid Spin and Defog. Its typing also shines both defensively and offensively, especially on offensive Nasty Plot/Air Balloon sets. It's one of the best users of Terastallization in my opinion, and I have seen both Tera Fighting and Fairy variants work well. Over-reliance on Air Balloon and its middling speed tier are its downfalls, as it loses the ability to check important Pokemon like Great Tusk and Clodsire if it loses its balloon. Scarf is definitely a viable set, but its never quite strong enough to handle its checks without some help, especially with the drop from Make it Rain. Still, I think the utility Gholdengo provides to offensive hazard-focused teams is too much to pass up. With the sheer number of excellent hazard setters this gen, I will be interested to see how the meta continues to develop around hazards if this guy maintains his prominence. I could see Gholdengo warranting a suspect if teams are generally unable to reliably remove hazards.
Lastly, one of these two guys has felt like a staple on most of my teams, probably because they are currently the best options for hazard removal because they can handle Gholdengo (if its balloon is popped). The fast and bulky BE Great Tusk set njnp posted the other day is so easy to win games with, but it really wants both Knock Off and Rapid Spin as the fourth move. Still, even behemoths like Palafin and Chien-Pao lose to the set after one boost. Iron Treads wishes it got Bulk Up, but still manages to be effective with its broader utility and better Speed. Overall, both of these two will have a solid place in OU I think. Wild to think Gamefreak actually made Donphan good.
Terastallization
I do think that Terastallization is a pretty fun and interesting mechanic to play around with, but I ultimately think the mechanic is too versatile and unpredictable to be competitive. Offensive terastallization in a vacuum is something on the power level of Z-moves in my opinion. Gaining a third STAB from a Pokemon with an already vast movepool or through the reasonably powerful Terablast is very strong. Similarly, an Adaptability boost on any natural STAB typing is very strong. Being able to choose either one with effectively no drawbacks and no indication of which you might be to your opponent? Now we are starting to get into unbalanced territory where its impossible for a Pokemon to be a guaranteed check to any offensive Pokemon.
Somehow, though, defensive Terastallization feels even more unbalanced and unpredictable. The power level of a defensive Terastallization feels akin to the power of a defensive Dynamax, as you can turn your opponent's would be sweep into a straight up L by surprising them with a Tera type that resists whatever move they were going for. Even if the player on the defense only gets one turn from the Terastallization, that can still be more than enough to turn the tide of the battle. The mind games and 50/50s this can force don't really have a place in a balanced and competitive metagame.
When no Pokemon can reliably check or overpower another Pokemon, we will inevitably get to a position where the player who Terastallizes first is usually at a severe disadvantage, which feels very similar to how Dynamax played out last gen. On top of that, selecting a Tera type comes with absolutely no drawbacks, even if it isn't used in the match. The solutions I have seen offered (mainly revealing Tera type at team preview or restricting Tera to one known Pokemon) feel like meager attempts to keep a broken and uncompetitive mechanic around. I can't even begin to think of the mind games that would come from selecting Tera types you had no intention of using.
Ultimately, Terastallization needs to go from OU.
Edit:
@below
Multiple things can be true at once. While sub-pass may not have been the reason BP was banned, the idea of passing a benefit along to a teammate is still there and is still overpowered. The comparison seems pretty valid to me.
