Okay, we got an expectedly massive shift. I'll post my early thoughts. Keep in mind these predictions might end up completely wrong but its worth a shot at least with all this chaos going on right now.
Broken:
: Last gen this ended up getting the boot for its versatility, good defensive typing, and shockingly good power. With less power creep, guess what issue rises back up again? And with Rain now in the picture? Yeah no way this stays.
: Head Smash nukes most things in the meta, Close Combat getting added wrecks potential checks otherwise like G-Fisk. This thing is unwallable outside of Sandaconda (who will probably rise back to NU since we lost Mudsdale) and Gurdurr. Maybe Tangela too if you're generous.
: So uh, Thousand Arrows means traditional Ground checks don't beat this. Quite fast, decently powerful for the tier otherwise, again only checked by Tangela (who is destroyed by Toxic) and fucking Aromatherapy Eldegoss lol.
: Going out on a limb with this one. But on paper, this thing's ability to support teams is just nuts, and NP benefits from less of a power creep surrounding it (oh and it got Hurricane this gen), and doesn't have that many checks.
Sun and Rain: Sun gets a mention based on Ninetales alone. The only things that check NP Ninetales with Drought are stuff that's already borked to begin with. If Ninetales gets the boot, Vulpix sun has some decently strong options like Exeggutor as well. But Rain is IMO more of a problem child. Sea horse aside, we have Pokemon that can easily sweep offensive builds like Qwilfish, Drednaw, Ludicolo, and even Carracosta. Your best Rain checks boil down to Jellicent, Vaporeon, and Cradily, which all get handled easily depending on the Swift Swimmer(s) being used.
Most of below is mainly predicated on the above getting the boot.
Great (S to A rank):
: More Fire-types the better, and I'd say Magmortar is a damn good Fire-type. Great coverage and benefitting heavily from Boots, it suffers from a lack of a boosting move compared to Ninetales and less speed. But its much stronger right off the bat, and Flame Body helps keep U-turn spammers (*cough* Ninjask *cough*) in check.
: Losing Hidden Power blows for this thing, but otherwise it still remains a solid wallbreaker that can go both physical (notably helps vs Centiskorch, and other Fire-types in general) and special. Good speed tier to boot. I can see it hitting its stride if/when Crobat gets banned. Escavalier completely counters it though which means you'll need a Fire-type as a partner for this thing.
: With good bulk, a typing good enough to check several Pokemon here actually, Power Whip as anti-Water coverage, 2 solid abilities, a boosting move, and more, Centiskorch is a damn fine Pokemon. I know some might say this is broken but I think it could be manageable.
: Simple mon to explain really. WishPasser + bulky Water. Nothing more to it than that.
(Fairy): Good support options and typing, has Fire-type coverage for Steels. Like all Silvallys no recovery but I think it'll be the best Vally in the tier.
: Quite a solid wallbreaker with good coverage and power, but not great Speed and a Fairy and Fighting weakness hurt it. Still, we basically have no real Dragon checks and this can decently reliably beat both non-Silvally Fairies and Steels.
: Nasty Plot does help this thing a good amount, and it gets good coverage to boot. Healing Wish and Rocks utility is nice, probably a lot better than it was last gen that's for sure.
Good (B tier at least, maybe lower A for some of these):
: Benefits from Hidden Power get yeeted and from Boots, and provides a decent support role with Defog and Heal Bell among others. Neat typing as well.
: Not great against offense, solid against more bulky teams. Good power with a boosting move in Swords Dance, but a mediocre speed tier for an offensive mon ain't great for it.
: Body Press means you aren't passive against Steels anymore. Has a solid niche over other Rockers because of its sheer physical bulk, ability to check Fire-types decently well, and the list continues.
: Power de-creep and Close Combat really helped this thing I must say. Again though, Escavalier. Might be underestimating this.
: A decent blanket physical wall akin to Tangrowth in higher tiers. Typing could be better but could be worse.
: Teleport helped this thing a good amount. Typing ain't great but it'll be one of our better removers from the looks of things.
: See Claydol, but replace Teleport with how this thing checks Ninjask and (the soon to be banned likely) Crobat. I have less confidence in this though because it fails to check Fire-types and the typing in general is bleck.
: A spinner with good Speed, reliable recovery, and a nice offensive option in Freeze-Dry. Also a defensive Ice-type which hurts it a good amount, but the Speed makes this quite solid when compared to say Avalugg.
: Lovely Kiss and Dry Skin give this a good niche as a sweeper. The type is iffy though with things like Sneasel running around. Still a solid sweeper.
Niche (lower B to C at most):
: Has a weird defensive typing that can work against things like physical Sceptile, most of our Water-types, decent-ish Fire check. But the typing brings several notable weaknesses as well, and there's better Rockers at there.
: Will probably be usable if/when T-rex gets the boot. A decent-ish wallbreaker but hampered by a 4x Fighting and Ground weakness and being quite slow.
: Poltergeist is nice at the very least, and STAB Sucker Punch as well, but not the strongest mon in the world, and losing Pursuit blows chunks for it. Absol just seems way better.
: Truthfully on the same level as Aromatisse, but a Fighting weakness really hurts it. A bit passive too.
: It'll probably do what it did in last gen's PU. Be either a Shell Smash sweeper (who lost Hidden Power Grass most notably which stinks but oh well), or a Rocker, and it does a decent enough job at both. Typing is just not good in the meta though.
: Will prove to be worthwhile as long as Hail teams are relevant with Arctovish. Can be a decent wallbreaker and Rocker but shat on by Escavalier. Not sure whether to put in Niche or Good, its viability mainly coincides with Hail's viability right now.
Trash (Unranked):
: On paper better due to Boots, but has way too many weaknesses to work as a hazard remover, and too slow and outclassed even by things like Aggron as an offensive mon of its typing. If Avalugg wasn't any good this won't be either.
: Worse Exeggutor, who isn't even good.
: Why didn't this drop to PU lol.
: Still too surprisingly weak to really work, and we have several better Electrics.
: We have two way better Rock Head Head Smashers and another way better Water/Rock don't use this lol.
: Worse Lapras and Lapras ain't viable here. Gaining SD is neat I guess but ultimately a gimmick at most. If you want a Water/Ice wallbreaker use Arctovish in Hail cause that's the best bet right now.
NUBL:
A rather short section, aside from maybe Croak I don't see any of these staying for very long. The Dragons have no real defensive checks (Eggy might be salvaged from the Ice weakness but probably not), Haunter helps from the fact we have not that many Ghost checks, Sneasel's combination of good power and Speed way offsets its terrible bulk and defensive typing, Tauros is way too strong and requires use of things like Regirock to have a fighting chance against it, and Porygon2 is way too bulky for the tier to handle really even with our Fighting-types.