Here are some important buffs to the regular Pokemon

Persian-Alola @ Heavy-Duty Boots
Ability: Fur Coat
Tera Type: Dark
EVs: 252 HP / 4 Def / 252 Spe
Jolly Nature
- Taunt
- Parting Shot
- Spikes
- Knock Off
Persian-Alola is still very niche, but it's not a lot more useful with Spikes. It's fast and bulky on the physical side thanks to Fur Coat. It's great at disrupting multiple ways. It can taunt hazard and set up, parting shot to weaken attacks, set up its own spikes, and knock off items like Heavy Duty Boots. It gives Persian a more compact role on a team that lower tiers are gonna feel for sure.

Roserade @ Heavy-Duty Boots
Ability: Natural Cure
Tera Type: Grass
EVs: 252 HP / 252 Def / 4 SpD
Bold Nature
- Mortal Spin
- Rest
- Spikes
- Shadow Ball
Roserade gaining access to Mortal Spin provides it with a hazard removing niche. It having more longevity than Glimmora with better bulk and Rest + Natural Cure (or you can use Synthesis), it can stay in the game to spin away hazards and also set up Spikes/Toxic Spikes itself.
And it needs Shadow Ball to threaten Gholdengo, who is back.

Rotom-Wash @ Leftovers
Ability: Levitate
Tera Type: Electric
EVs: 252 HP / 252 Def / 4 SpD
Bold Nature
IVs: 0 Atk
- Parting Shot
- Hydro Pump
- Will-O-Wisp
- Pain Split
Oh btw they decided to give Rotom Parting Shot. You know, the best pivot move in the game? Rotom gets it now and doesn't have to care about Ground types blocking its pivoting action. This is absolutely crazy.
Cofagrigus @ Heavy-Duty Boots
Ability: Mummy
Tera Type: Ghost
EVs: 248 HP / 8 Def / 252 SpD
Sassy Nature
IVs: 0 Atk / 0 Spe
- Pain Split
- Will-O-Wisp
- Hex
- Parting Shot
Cofagrigus also got Parting Shot, which is also a pretty big buff. Cofagrigus acts as a discount Pecharunt. Pecharunt itself is not available, so its less competition. Even if it were here, Cofagrigus actually sets itself apart from Pecharunt with its speed stat. Cofagrigus actually speed ties the Slow twins. The Slowtwins of course have Teleport, but Galarian Slowking only has Chilly Reception. That does mean Cofagrigus can run minimum speed and could Parting Shot after Slowking-G Chilly Receptions.

Keldeo @ Choice Specs
Ability: Justified
Tera Type: Water
EVs: 4 Def / 252 SpA / 252 Spe
Timid Nature
IVs: 0 Atk
- Scald
- Secret Sword
- Ice Beam
- Earth Power
Keldeo got a massive movepool buff with access to pretty crucial coverage moves in Ice Beam and Earth Power.
Ice Beam allows Keldeo to hit the many Dragons, Grasses, and Flyings that could previously wall its STABs. This is a great improvement over Icy Wind that was way weaker and inaccurate too.
Earth Power allows Keldeo to hit many bulky Waters that resist Fighting that aren't Flying, such as Toxapex and Primarina. You also hit Pokemon like Volcanion harder too.

Runerigus @ Leftovers
Ability: Wandering Spirit
Tera Type: Ground
EVs: 252 HP / 4 Def / 252 SpD
Sassy Nature
IVs: 0 Spe
- Parting Shot
- Will-O-Wisp
- Earthquake
- Knock Off
This is pretty much Cofagrigus but physically based and with Ground typing. Additionally it also gets Knock Off now.

Indeedee-F (F) @ Terrain Extender
Ability: Psychic Surge
Tera Type: Psychic
EVs: 252 SpA / 4 SpD / 252 Spe
Timid Nature
IVs: 0 Atk
- Wish
- Moonlight
- Moonblast
- Expanding Force
This isn't so much an actual set since Indeedee got massive moves too. Still only pivot move either gets is Baton Pass. But adding Recovery, Wish support, and giving Indeedee stronger Fairy coverage is fantastic. It can better support its team with Psychic Terrain by lasting longer and healing up teammates too.

Overqwil @ Black Sludge
Ability: Intimidate
Tera Type: Dark
EVs: 252 Atk / 4 SpD / 252 Spe
Jolly Nature
- Parting Shot
- Thunder Wave
- Barb Barrage
- Crunch
Overqwil got Parting Shot, which is great since it also gets Intimidate. It gets Thunder Wave too, which is nice to status Steel and Poison types.

It gets Surf now, which is super relevant in its match up against Great Tusk and Iron Treads.
Those are the biggest buffs imo of non-Mega Pokemon.