I made a chart on Alolan Pokemon and which Pokemon were still eligible to get a new form. I made it with the following rules:

>It's likely exclusive to Gen I unless an official announcement proves otherwise
>Legendary Pokemon are likely exempt
>Pokemon that evolve into a Pokemon outside of Gen I are likely disqualified
>If it was shown in an official trailer, it's likely not getting an Alolan Form
>If a final evolution is disqualified, all of its previous forms are as well
>If the beginning or middle of an evolutionary line is disqualified, it doesn't necessarily disqualify the final form of the line (i.e Poliwrath and Vileplume)

https://docs.google.com/spreadsheets/d/1_Pjom65jeMXy632tkFKgk5RE8-KbeSO182mP_EZPUd0/edit#gid=0

After watching through a bunch of the American and Japanese trailers, I've come to the conclusion that the following Pokemon are still eligible:

>Caterpie Line
>Weedle Line
>Pidgey Line
>Rattata Line
>Ekans Line
>Nidoran-F Line
>Nidoran-M Line
>Clefairy Line (Though it just got the Fairy-type last Gen)
>Jigglypuff and Wigglytuff (Though they just got the Fairy-type last Gen)
>Vileplume
>Paras Line
>Venonat Line
>Diglett Line
>Golduck
>Poliwrath
>Abra Line
>Bellsprout Line
>Tentacool Line
>Geodude Line
>Ponyta Line
>Farfetch'd
>Seel Line
>Grimer Line
>Cloyster
>Drowzee Line
>Krabby Line
>Voltorb Line
>Hitmonlee and Hitmonchan
>Koffing Line
>Goldeen Line
>Staryu Line
>Mr. Mime (Though it just got the Fairy-type last Gen)
>Jynx
>Ditto
>Vaporeon, Jolteon and Flareon
>Omanyte Line
>Kabuto Line