There haven't been nearly enough hot takes in this thread so I thought I would start proto-vr discussions and invite others to call me an idiot. It's a bit rough and imprecise (Don't ask me why something is in A instead of A- or whatever) but everything B+ and above is good I think is good, everything B- and above I think is more than a gimmick.
S rank: I think

Slowbro and

Toxtricity are undeniably the best offensive and defensive pokemon in the tier. Slowbro is a versatile physical wall with
4 moveslot syndrome diverse move options that matches up well against almost all physical attackers. Building with Slowbro is so much easier than building without. Toxtricity has no switch ins, that's all. Our best ghost types are almost all flying types and our best specially defensive steel types still takes almost half from a non-tera boomburst. Palossand is one wrong guess away from being turned to dust and if you switch a sac in on a predicted boomburst then see it click shift gear you might have just lost the game.
The A+ rank mons are ones I think are the best at what they do.

Flamigo and

Tauros are the best attackers in the tier that shouldn't be banned, Flamigo is the best scarfer and one of the best choice banders in the tier, and Tauros does both of those almost as well while also having bulky sets or bulk up as options. Intimidate is not as useful as you would think since the best physicalk attacker is immune to it, but it's still a great ability for handling the likes of Heracross.

Klefki is the best steel in the tier and makes spike stacking teams very good.

Revavroom is the second best steel in the tier and one that can be splashed on a lot of teams. Offensive and bulky sets are both good and toxic/tspikes are a rare commodity in this tier.

Bellibolt is always good, if you have one ground type on your team then you do not have a ground type on your team.

Is amazing and versitile. It's our best defogger and our best sweeper, it can be bulky or fast and it's our only true resist for flamigo. All the other oricorios are mostly just pompom but worse.

sensu is probably a better quiver dance sweeper in a vacuum, but it lacks the little things that pompom has. Fire has a niche, but it basically needs a team that has a very specifically shaped hole.
Rotom-heat is a gross breaker. With a nasty plot up nothing switches in, most of the tier gets ohkoed and it can conveniently avoid ohkoes from a lot of faster mons. You both can't afford to let it set up a free plot and can't afford to give it a free attack because you're trying to not let it set up.
As much as I hate it,

Tatsugiri is our best spinner. It's always a risk to spin with this thing but it has a nice speed tier and is the only spinner that beats all the ghost types.

Mudsdale is our best rocker and the easiest to fit on a lot of teams. It's bulky, still hits like a truck and a horse that can roar sounds pretty scary. Only problem with it is that it's the ground type that gets destroyed the most by Bellibolt.
Below the A+ I won't talk about everything, just the ones I really want to make a point about.

Palossand is the best way to make a team not lose instantly to toxtricity and having a rocker with recovery is nice. I definitely feel like it's falling off a bit, it's too passive and exploitable and sometimes just has to rely on 30% sludge bomb poisons to make any lasting progress.

Arboliva is the mon I will hype up for as long as I live, nothing in the tier makes progress like this thing does, and it's impossible to kill because of grassy terrain and its choice of leech seed or specs giga drain. It gets a lot of good switch in opportunities against the grounds or slowbro (depending on the set) and then it can click buttons and heal all its health back.

Krook is a jack of all trades and a master of a few. It's a decent scarfer, a good choice bander and our only stealth rock setter with an actual speed stat, so it's easy to fit on offensive teams.

This thing feels like it should be so good, but it's kind of awkward. I'm sure we will eventually find the perfect build though, so it gets a nice rank.

Ladder seems to hate using Missy, but it's still an amazing sweeper with a scary speed stat. Nothing faster really wants to switch into an attack and nothing slower wants to take a +2 shadow ball or coverage move. Taunt and draining kiss also make it very strong into fat teams

I think Braviary is our best defogger right now due to its good stats and access to u-turn, though that is a very low bar. It's like a fat Crobat and can take a surprising amount of neutral hits very well. Its main downside is its low speed stat and defog sets can invite in some nasty electric types. Bulk up sets are also very good and could punish defoggers pretty hard if anyone was using that move for hazard removal.

I think Sylveon is our best fairy type and wish passer, it can invest in physdef to be a good mixed wall and gives wish support to stuff that needs it while not being too passive like Almomomola.

I don't know how to rank hail, but Cetitan is very scary with a belly drum and it is surprisingly easy to get a drum off.

The other steels are alright, I think Bronzong is only good with ironpress with either rest or wish support though and you shouldn't try running stealth rock on either of them.

These 3 spinners I think are decent, but they just have so many flaws and have to tera too much for me to want them as defensive mons. Cryogonal is the best in my opinion because it matches up well against a lot of special attackers without needing to terastallize and special ice attacks do more to the common spinblockers than physical ice attacks from Avalugg or whatever Coalossal tries to do to them. Also haze cryo is good at keeping Oricorios or the bulky calm minders in check.
Here's a tiermaker if anyone else wants to make a list, I think I got everything in the roles compendium and a few more pokemon that have a niche.
https://tiermaker.com/create/sv-ru-tierlist-maker-15619723