Quick question: Looking at Vulpix’s pokedex entry from X, it mentions that vulpix are born with ‘just one snow-white tail’. Do you think this was foreshadowing for Alolan vulpix and do you think there is anything more you can make of this?
If that line were new in the X Pokédex I’d say yes, but it actually appeared previously in Leaf Green, and the idea of Vulpix being born with a white tail goes all the way back to at least the original Pokémon Stadium (Red and Blue specify one tail at birth, but not the colour). It could be deliberate foreshadowing that they chose to recycle that particular line in generation VI, but X and Y reuse a lot of Pokédex lines from Fire Red and Leaf Green for the Pokémon that were around in generation III, so I think it’s more a nice coincidence than anything else.
Vulpix is a kitsune fox spirit, which grow more tails as they become older and more powerful, and turn white or gold when they get to nine tails, which is why Ninetales is a pale gold colour. I don’t think their first tail is supposed to be white, though. Nor are real foxes born with white tails that later turn red, as far as I know. A lot of animals have special juvenile colouration that provides them with better camouflage while they’re young and vulnerable, but I don’t think white would help with that (unless you lived in a snowy area, which… well, Alolan Vulpix says hi). It could just be meant as foreshadowing of the evolution to Ninetales, I suppose.