No new Reigonal Forms in this game as it takes place only soon after Pokemon XY. There are new megas and new evolutions though.

New Evolutions:
Diggersby New Evo (Normal/Ground)
Gogoat New Evo (Grass)
Heliolisk New Evo (Electric/Fire)
Hawlucha New Evo (Fighting/Flying)
Ledyba New Evo (Bug/Psychic)
Ariados New Evo (Bug/Poison)
New Eeveelution (Dragon)

New Mega Evolutions:
Mega Serperior (Grass/Dragon)
Mega Cinderace (Fire/Electric)
Mega Empoleon (Water/Ice)
Mega Dragonite (Dragon/Flying)
Mega Jynx (Ice/Fairy)
Mega Flygon (Dragon/Ground)
Mega Luxray (Electric)
Mega Skarmory (Steel/Flying)
Mega Haxorus (Dragon/Steel)
Mega Hydreigon (Dragon/Dark)

Xerneas and Yveltul have new “Alpha Forms” and there is One new legendary Pokémon called Adrazyl and it is The Chaos Pokémon, Zygarde’s Counterpart, and seemingly what the ultimate weapon was based on.

Game will release on February 7th 2025