Possible Alolan Forms

Pidgey-Pidgeot
Ekans-Arbok
Nidoran F-Nidoqueen*
Nidoran M-Nidoking*
Clefairy-Clefable
Vileplume
Venonat-Venomoth
Persian
Bellsprout-Victreebel
Tentacool-Tentacruel
Geodude-Golem*
Ponyta-Rapidash*
Doduo-Dodrio*
Seel-Dewgong
Grimer-Muk*
Hitmonlee
Hitmonchan
Koffing-Weezing*
Goldeen-Seaking
Mr. Mime
Jynx
Omanyte-Omastar
Kabuto-Kabutops
Articuno
Zapdos
Moltres
Mewtwo
Mew

Animals to watch out for (not from the above leak):

Snowman
Dolphin
Normal/Multi-Type Cat
2 Fossil Families

Likely to Evolve (or Pre-Evolve):

Komala
Drampa
Bruxish
Salandit
Mimikyu
Wimpod
Bounsweet
Comfey
Oricorio
Minior
Morellul
Pyukumuku
Turtonator
Crabrawler
Jangmo-o (likely Pseudo-Legendary)
Passimiam
Oranguru
Solgaleo/Lunala???

20%-25% Alolan Forms, around 100 new Pokémon. Few more Ultra Beasts. That's what appears to be shaping up for the new Pokémon game.