These are the remaining possible Pokemon that will get Alolan forms. This is making the assumption that

>only gen 1 pokemon will get alolan forms
>anything with a mega evolution won't get an alolan form
>anything with a cross gen evo won't get an alolan form
>all the NFEs that have confirmed alolan forms will have alolan form evolutions
>anything that shows up in a trailer/official promotional material without an alolan form isn't getting an alolan form

this has been reliable so far because under this criteria, grimer/muk wasn't eliminated until today and literally the only pokemon that has been confirmed an alolan form while showing up in its regular form is meowth, and that's only because it's your mom's and they explicitly state your character moved from another region.