Answered Alolan forms

[Z13k5ry]

How do you evolve cubone into Alolan marowak?

And how do you get other alolan pokemon?

[Patrick]

Pokémon that evolve to an Alolan form from their regular form (E.g. Cubone -> Marowak (Alolan)) need to be evolved while you are on or completed the Alolan Sidequest region.

Pokémon that are caught in an Alolan form and evolve to Alolan forms (E.g. Diglett (Alolan) -> Dugtrio (Alolan)) need to be caught while you are on or completed the Alolan Sidequest region but can be evolved at any time.

 

Note: When you reset your sidequest progress, you will no longer be able to evolve a regular form Pokémon to an Alolan form and you will no longer encounter Alolan forms on the maps until you make your way back to/past the Alolan Sidequest region again.

[eurstin]

You need to catch Cubone (Alolan), not Cubone. Same applies for others, although some (like Vulpix (Alolan)) require an ice stone to evolve them. You need to complete sidequests 100% to have a chance of getting one.