Some of this will be revealed in a trailer at the start of september, believe it if you want

* = confirmed in prior leak

EVO'S OF KNOWN POKEMON:

Grookey > Bandrill (Grass) > Temporilla (Grass/Rock)

Scorbunny > Raboot* (Fire) > Volthare (Fire/Electric)

Sobble > Sizzile* (Water) > Intelleon* (Water/Ghost)

Wooloo > Fleecee (Normal/Fairy)

Picachick (Normal/Flying) > Corviknight

Rolycoly > Combustore (Fire/Rock) > Locomocoal (Fire/Steel)

Yamper > Sparkett (Electric)


Legendaries:

Eternatus* (Fire/Ghost)

Limbra (mythical) (Normal/Ghost)


NEW POKEMON:

Skwovet* (Grass/Normal) > Greedunt* (Grass/Normal)

Psyfin (Water/Psychic) > Dolphellum (Water/Psychic) dolphin pokemon

Pixopy (Poison/Fairy) based on a corrputed fairy

Forminy (Bug) > Formaqua (Bug/Water) OR Informo (Bug/Fire) (regional bug, based on ants)

Allodon (Steel) > Duraludon > Titaneodon (Steel/Dragon)
GALARIAN FORMS:

Meowth/Persian (Ghost)

Farfetch'd (Fighting/Flying) > Sirfetch'd* (Fighting/Flying)

Ledyba (Poison/Bug) > Ledian (Poison/Bug) > Ledinox (Poison/Bug)

Frillish/Jellicent (Water/Electric)

Seviper (Grass/Dark)

Overall there are 107 new pokemon, including Galar forms and Galar form exclusive evolutions
GYMS:

Apart from the ones already revealed, there's:

Opal (Fairy)*
Kabu (Fire)*
Ariella (Flying)
Auren (Ground)
Krysta (Ice)

I'll be hanging in replies, AMA