Oh boy, this'll be fun. Bolded my new additions that I think will eventually make the VR.
If I have time later I'll do write ups for the new additions to justify them, because I think some might view it as... well, just strange without explanation. I've explained the new mons that were included at the bottom. Poor Hariyama doesn't get to be on the list after Chi Yu went to fish heaven.
S Rank:
(Pokemon I feel are very splashable on any team and are versatile in the sets they can run)
S Rank

Gholdengo

Great Tusk
S- Rank

Chien-Pao

Dragapult

Iron Valiant
A Rank:
(Pokemon I feel help shape the metagame and make it what it is, whilst having some weaknesses to them to keep them balanced)
A+ Rank

Cinderace

Dondozo

Dragonite

Espathra

Garganacl

Kingambit

Roaring Moon

Ting-Lu
A Rank

Amoonguss

Clodsire

Corviknight

Iron Moth

Rotom-Wash

Skeledirge

Volcarona
A- Rank

Breloom

Garchomp

Glimmora

Grimmsnarl

Hatterene

Iron Hands

Iron Treads

Meowscarada

Scizor

Toxapex
B Rank:
(The Pokemon I feel hold a certain niche in the metagame and require specific teambuilding to allow them to actually be good, or generally have one role in the metagame)
B+ Rank

Azumarill

Baxcalibur

Pawmot

Pelipper

Quaquaval

Slowking

Tauros-Paldea-Fire

Torkoal
B Rank

Barraskewda

Ditto

Floatzel

Orthworm

Sandy Shocks
B- Rank

Ceruledge

Gastrodon

Hydreigon
Golduck

Slither Wing

Talonflame
Toedscruel
C Rank:
(the garbage mons that hold some form of value individually pulling off some form of niche viability)
C+ Rank

Alomomola

Blissey

Gyarados

Hawlucha

Hippowdon

Iron Thorns

Iron Jugulis

Masquerain

Pincurchin

Polteageist

Scovillain

Scream Tail

Tyranitar
Vaporeon
C Rank

Arcanine
Avalugg

Charizard

Cloyster
Dragalge

Gallade
Grafaiai

Indeedee

Lokix

Magnezone

Mimikyu

Rotom-Heat

Slowbro

Sylveon
Tauros-Paldea-Water
Tinkaton
D Rank:
(the garbage mons)
D Rank

Brute Bonnet

Cetitan

Chansey

Gengar

Haxorus

Kilowattrel

Klefki

Maushold

Quagsire

Rabsca

Salamence

Umbreon
New mon explanations:
Golduck
Rain team's best and really only special sweeper, NP+3 moves is very difficult to wall after your checks are softened up. Very underplayed but given the right conditions, it will punch holes through teams. Only viable on rain teams but this doesn't stop Barraskewda and Floatzel from being highly regarded.
Toedscruel
Great resists and the only mon to be able to status Gholdengo and Garganacl, some of the most important mons in the tier. Great coverage and utility. Rapid Spin and Knock Off with hazards is great role compression, can run Spore or Toxic for status, and Earth Power is the only STAB really needed on most sets to threaten key mons. A ton of flexibility and roles it can fill, honestly a relatively unexplored option in the metagame.
Vaporeon
I'll continue to link this until Vaporeon gets ranked.
Avalugg
One of the better defensive Tera mons, enormous defense with Recover+Rapid Spin is pretty valuable, and Curse/Iron Defense+Body Press sets can win games if positioned correctly. Oh by the way this thing gets Sturdy+Mirror Coat if you really want to lure mons like Gholdengo. Ice Body+Leftovers with Slowking Chilly Reception on Balance or Stall is super underrated.
Dragalge
Nominated here. I love the AV set to blanket check most special attackers, but Specs against Balance and Bulky Offense just wins games. Lots of Tera possibilities, and Poison coverage to threaten the Fairy types wanting to switch into Draco Meteor makes this mon difficult to switch into. Adaptability working with Tera is surprisingly powerful, even without Specs.
Grafaiai
A very unpredictable mon with a lot of utility options. People have explored the Prankster Parting Shot pivot set, but the Poison Touch set I posted
here is really difficult to handle for many teams. Taunt/Encore is great to cover set up and stall, and Black Sludge Switcheroo can cripple walls. A bit on the frail side but still a ton of options to explore.
Tauros-Paldea-Water
When you want a water mon to check Chien Pao and you don't want to play Azumarill or Quaquaval. RestTalk is probably its best set, but mixed bulk AV is pretty effective with Wish support. Don't sleep on its offensive sets either, Bulk Up+3 moves can catch unprepared teams off guard and sweep, you just have to choose between Wild Charge and Earthquake for what you want to hit. Not anywhere near as good as its Fire counterpart, but still a ton of fun.
Tinkaton
Great typing and an excellent support movepool. Gigaton Hammer is a great exclusive, and you have Stealth Rocks, Knock Off, Encore, and Thunder Wave to choose from to round out the arsenal. People have tried the SD set but I think its pretty mid. Pretty poor offensive stats is disappointing but it has arguably the best dual typing in the game and good enough bulk and movepool to make it work. Also a great Chien Pao emergency button if you need it. One of the few Mold Breaker mons that can status Gholdengo and Garganacl, and if you really want to run SD, you can actually break through Unaware defensive cores while being immune to Toxic.