Arcanine-Hisui (#49, 3.391%)
Despite a merely good attack stat of 115, Hisuian Arcanine was an solid wallbreaker to due it STAB combo of Head Smash and Flare Blitz alongside the always great Extreme Speed.
Articuno-Galar (#66, 1.545%)
Articuno used its good all round stats combined with Calm Mind and Agility to become a powerful Stored Power sweeper, its lack of coverage and poor defensive typing was made up for with Tera Fighting Tera Blast.
Azelf (#87, 0.818%)
Azelf is a fast and powerful attacker with a wide movepool of coverage and utility moves available allowing its to also act as a suicide lead.
Basculegion-F (#54, 2.637%)
Basculegion-F was a very threatening wallbreaker in the rain utilizing Swift Swim or Adaptability to blast through teams with its Specs and Rain-boosted STAB Hydro Pump.
Basculegion-M (#53, 2.640%)
While not being able to live out its dream as an Uber with the ban of Last Respects, Basculegion-M is an extremely powerful wallbreaker in the Rain with its terrifying Wave Crash being one of the most defining parts of the archetype.
Braviary-Hisui (#64, 1.648%)
Braviary-H is an interesting special attacker with two good abilities in Tinted Lens and Sheer Force allowing it to make up for its relatively unimpressive power as well as its signature move, Esper Wing, allowing it to boost its poor starting speed.
Cresselia (#44, 4.047%)
Cresselia is an incredibly bulky Pokemon that is able to utilize Tera and Levitate to turn into a nigh unkillable menace. From there, Cress can set up Calm Minds for a Stored Power sweep or support its team with Lunar Dance and Trick Room.
Decidueye-Hisui (#81, 0.959%)
Decidueye-H is a bulky attacker with access to a strong movepool including both Defog and Roost along with the ability to threaten Gholdengo with Knock Off or with Triple Arrows, which is frankly one of the most ridiculous moves in the entire game, especially when combined with Scrappy.
Diancie (#109, 0.319%)
Diancie's 150 base defenses, unique typing, and wide movepool allow it act as a support mon with Stealth Rock and Encore or it can also try its hand at Stored Power sweeping with Calm Mind, Iron Defense, and Diamond Storm.
Electrode-Hisui (#90, 0.782%)
Electrode-H is indeed very fast, the fastest in all of OU, allowing it to freely Volt Switch around while threatening Ground types with its high BP STAB Grass moves.
Enamorus-Therian (#47, 3.559%)
Enamorus-T is a very bulky and very strong special attacker able to slowly snowball with Calm Mind and occasionally Iron Defense into an absolute tank while staying healthy with Draining Kiss.
Glastrier (#98, 0.506%)
Glastrier is able to make full use of its excellent stat spread as a niche pick on Trick Room teams, becoming a sort of pseudo-Mamoswine with its Ice and Ground coverage to break through teams.
Goodra Hisui (#68, 1.483%)
Goodra-H possesses an excellent defensive typing, incredible special bulk, and all the coverage moves it could want, though it wouldn't mind some recovery.
Kleavor (#59, 2.079%)
Kleavor is able to use its signature move, Stone Axe, to actively set up Rocks as a lead or as a pivot with its great attack stat and STAB U-Turn.
Lilligant-Hisui (#45, 3.740%)
Lilligant-H is lucky benefactor of physical Quiver Dance, Victory Dance, allowing it to become incredibly dangerous under the Sun with Chlorophyll and STAB Solar Blade. Lilligant can also run Wide Lens sets with Hustle for an free Atk boost and a more accurate Sleep Powder.
Meloetta (#101, 0.431%)
Okay, I'm sorry, Meloetta has nice stats, but I have no idea why anyone used it in OU.
Mew (#65, 1.561%)
Mew is obviously the most customizable Pokemon in the game though its most common sets are its lead set with Rocks and Taunt and the Demon Mew set with Calm Mind, Iron Defense, and Stored Power.
Moltres (#70, 1.438%)
With Boots, Moltres is a very effective defensive pivot, able to threaten physical attackers with Flame Body and hit back hard with its 125 SpA. Moltres effectively fills Talonflame's niche but with far superior bulk and power at the cost of speed and Defog.
Moltres-Galar (#51, 3.207%)
Moltres-G is able to utilize its Double Dance set like in Gen 8 but now with the added coverage from Tera (usually Fairy) to become an explosive special sweeper.
Muk-Alola (#85, 0.910%)
Muk-A's awesome defensive typing and good special bulk allow it to sit in the face of some of the most powerful special attacker in OU and spam Poison Touch Knock Off on whatever happens to come in next.
Overqwil (#78, 1.034%)
Overqwil also has the excellent Poison/Dark typing along with two good abilities in Intimidate and Swift Swim. Overqwil adds an interesting wrinkle to Rain teams due to its STAB combination but does suffer in power compared to its Water-type counterparts.
Regidrago (#73, 1.364%)
Regidrago was somehow not nerfed in the transisition to Gen 9 and keeps its 50% boost to Dragon type attacks while also receiving a real coverage move in Earth Power giving it something else to think about before clicking Dragon Energy.
Rillaboom (#56, 2.466%)
Despite losing Grassy Glide, Rillaboom was still a strong support Pokemon with Knock Off, U-Turn, and of course Grassy Surge enabling powerful teammates in Sneasler and Heatran.
Slowbro Galar (#82, 0.943%)
fastest in da west.
Thundurus-Incarnate (#102, 0.400%)
Prankster Thunder Wave is cool, not as cool as it once was though. Tera Ice gives it STAB BoltBeam and can be decently threatening with its good attacking stats and Nasty Plot.
Thundurus-Therian (#58, 2.170%)
Like its other form, Thundurus-T benefits from the coverage Tera brings but is able to push it even further with its excellent 145 SpA making it one of the most instantly threatening wallbreakers and pivots in the tier.
Typhlosion-Hisui (#86, 0.898%)
Typhlosion-H takes over as the Eruption spammer of the game but now with the added benefit of a strong secondary STAB.
Uxie (#94, 0.538%)
Uxie's great bulk and utility movepool allow it to find a niche as a Screen setter with a variety of other tools such as Encore, Stealth Rock, Knock Off, and Trick Room.
Zapdos-Galar (#79, 1.016%)
With a good attack stat of 125 and a spammable STAB combo with U-Turn, Zapdos-G make a good Choice Scarf or Band user.
RU (>0.301%)
Avalugg-Hisui
Delphox
Houndstone
Zarude
NU (>0.151%)
Hoopa
Mesprit
Raichu-Alola
Tornauds-Incarnate
Wyrdeer
PU (>0.075%)
Articuno
Calyrex
Carbink
Dugtrio-Alola
Persian-Alola
Tauros