May I ask what your specific name for Alolan Vulpix is, if not Keokeo?
i typically do use keokeo! for regional forms that are already given names, i just use the canon names for them, even if it doesn't make a whole lot of sense in pmd canon specifically—but then again, a lot of core series pokémon things don't make a ton of sense in pmd canon, so i allow it. for some pokémon, however, i don't give them brand new names—this is usually for stuff like galarian forms. "snowslash" is inspired by the existence of "keokeo" in alola, but in galar, for example, i give galarian ponyta "clouded forest ponyta," both acknowledging its relation to ponyta as well as referencing the way that it was initially revealed, with that like. 24 hour long stream of a fairy-lookin misty forest in galar where it showed up right at the end