Oh boy, my obligatory unasked thoughts! Fun times galore. I've played about... 30-40 or so games at this point, so let me give my thoughts based on what I've seen.
DO NOT SLEEP ON MANTINE. Now that it has Toxic and Defog in its arsenal again, with HDB to bear and Dracovish running about, it finally has a more realized niche in the tier. Not only does it role compress incredibly well with access to Defog and Water Absorb, but its stat spread and defensive typing also lets it wall a surprising amount of the metagame with offensive Steel moves now so common. Additionally, its access to things like Haze, Tailwind (if you really want to use that), and Toxic lets it serve utility outside of Defog. On top of that, a decent SpAtk stat lets it hold a candle against Sub Hydreigon with Ice Beam, which would otherwise wall its defensive set.
Here's a replay to show an example of its defensive potential.
https://replay.pokemonshowdown.com/gen8ou-1062891175 It's most optimal to run with max Phys Def, as its special defense lets it already soak special hits well without need to invest.
Additionally, I've found some success running it with Swift Swim as well, letting it work nicely on rain teams as an offensive sweeper thanks to access to a menacing STAB Hurricane, something it has over stuff like Dracovish, Skewda, and Ludicolo on top of its ability to soak hits with its natural bulk. This lets it shred the new Musketeers. Rotom, Kyurem, and the new Zeraora give it a tough time, though.
However, its flexibility both offensively and defensively is something in this meta that is going to be extremely nice. To me, it feels like a less passive, more flexible Toxapex with a nifty ground immunity, which is unbelievably good in the meta right now. As I said, do NOT sleep on this thing.
I think Kyurem will have a good place in the meta with the ability to offensively stallbreak and shred balance archetypes. Freeze-Dry now gives it the ability to challenge a lot of bulky waters that walled it before, and given how many defensively powerful mons such as Seismitoad, Quagsire, and Mantine are becoming more prevalent, getting Freeze-Dry will allow it to easily cleave through these Pokemon. Earth Power and Freeze-Dry provide it with ubiquitous, perfect coverage that can pry apart most teams if unprepared, and its speed tier is legitimately nice atm. Unfortunately, though, the Musketeers and Melmetal running around give this thing some trouble, and its need of Metronome leaves it pretty hazard weak. Lefties and HDB are options to run on this set, though, and they're definitely viable.
Though, I want to bring attention to the option of running a Choice Scarf. Not only does this remedy the problem of being outrun by the Musketeers naturally, but it will always outpace scarfed Rotoms, and with Freeze Dry, Focus Blast, and Toxic at its disposal, it can act as a powerful wincon in the meta if unprepared.
I think this thing will be a great stall/balance breaker later down the line, but as of right now with AV Melmetal/Musketeers being so prevalent, it might need some support to fully realize its potential. But, I think this thing will be very solid eventually, and a strong Pokemon to have as a whole.
https://replay.pokemonshowdown.com/gen8ou-1062887537 Example of SubRoost doing some big boy work.
A bit overrated in my eyes with Melmetal's arrival and the Rotoms becoming even more common somehow. But, it is adapting extremely well by running LO Teravolt Earth Power/Focus Blast to cleave through its checks. I think this thing is definitely too much for the tier with the sheer power coming off of Dragon Dance boosted Spears/Dragon Claw/Fusion Bolt and the ability to easily adapt to its potential checks, making it an absolute pain to prepare for, but, it
could be managed, maybe (emphasis on the maybe, because I really don't like what I see). Let's just see how this plays out. It is only day 2-3 into Home, after all; though, the fact it's forcing Dragapult and Jirachi to run a Scarf almost by itself is kind of concerning.
What can I say about this thing that hasn't already been said? Absolutely amazing typing in mono steel rn, gargantuan physical stats that lets it shred almost any team archetype, and surprising flexibility in Band, AV, and Thunder Wave sets. Holy shit. This thing is a top tier Pokemon atm, and I feel like I don't really need to explain why without being redundant. Though, its inability to recover reliably, its speed, and the raising use of Rotom does heavily keep this thing in check, so I believe it's still manageable, but it's on the cusp of being one of the best mons in the tier at the moment (and a headache, at that). Similar with Kyurem-Black, I think we should wait this out and see whether it's broken or not--though, despite how potent it is, I think it's just barely manageable.
Despite how good in theory this thing has been made out to be, I find it odd how I haven't seen very many. It's great that it checks Rotom thanks to Volt Absorb, has the ability to naturally outspeed Dragapult (and threaten it with Play Rough) and has a ton of offensive options, though. I think this thing will have a very defined niche in the tier once the new toy syndrome does its time.
Incineroar has a niche, albeit not too big of one. Fire/Dark is an extremely nice typing in a meta where Ghost and Steel spam is nigh ubiquitous, and Intimidate is also cool to soften up the physical onslaught in the tier at the moment. I like that it has Close Combat as well as Parting Shot now, but... it kind of needs to run HDB to not die to hazards. I think it can be a super strong pivot in the right hands, though.
My attachment to this Pokemon makes me want to love it even more, and I'm happy to say that its new access to Calm Mind and its strong, synergistic dual STAB serves it nicely. It's similar to Incineroar where it's not fantastic, but it has a niche anyway since Azu is gone (for now, at least).
I loathe Arena Trap, and I hate that it's gotten even better with the new emphasis on Steel Pokemon. It's amazing to me that we keep unbanning it and keep trying to see if a mechanic that we've time and time again deemed broken is broken, and it keeps showing how ridiculous and constricting it always is. This thing is partners in crime with Venusaur, and Venusaur has made this thing even better indirectly by erasing things that otherwise check the former. I don't like that I'm seeing it on every other team now too with how incredibly good Melmetal is, and I don't like that it's even able to trap new things like Scarfed Jirachi/Terrakion and Zeraora with a new Scarf set I've seen time to time. You can't make any gutsy plays or play flexibly with Ground weak Pokemon if the threat of Dugtrio is still active, slowing down games and promoting an extremely unhealthy uncompetitive atmosphere. I'm not a fan of banning things, but... please, dear god, why hasn't this been addressed yet?
Sun is pretty much viable again because of Venusaur alone. Not only does it have a better setter in Torkoal to support it, but new access to Weather Ball and Earth Power have made this thing an absolute nightmare to face. Duggie being around also makes it even better, as I stated before. Don't sleep on this thing.
Overrated, though I think everyone is starting to see that now. Subpar offensive stats kind of hurt it a lot, and it's not like Cloyster where it has stupid bulk and a phenomenal ability/set of moves to support it. It's just... meh.
I'm unsure if it's the teams I'm using, or if I'm just not running into any good users of it, but... SubToxic Aegislash is nowhere near as bad as I thought it'd be. We're in a Steel based Meta rn with Melmetal around, and Ghost Spam (which is... ghost spam) is still an extremely potent way to threaten it. I've also found Taunt Bulletproof Kommo-O is a great hard counter to it, and doesn't even need to specialize in countering it as it can spec into providing Rocks and soaking physical hits as a whole. Still though, the addition of Toxic does give it an extra option, and a very good option at that. Its one negative matchup in stall is remedied by holding Toxic, which I believe will take it from being among the best to being a top 5 (maybe top 3) Pokemon in the tier. It's also cool that it checks Melmetal and Kyurem, giant threats atm.
May add more later, but this is the bulk of what I wanted to address.