I don't know your team, so I can't say. Really, part of how I make that kind of choice is type coverage, good moves, and Pokémon that mesh well together. I kinda overthink things too much in normal play though, and I don't overthink enough in competitive play, so my word isn't law. Crobats are good at certain things, Alolan!Ninetales are good at certain things. Wow, this comment is no help.
I'd keep the Zubat. But that's just me ¯\_(ツ)_/¯ I personally prefer to have Crobat on my team. They're hella fast, they have access to toxic and they fuck up fairy types. And they're bats, for fucks sake >:3
I already have mareanie though...
Try to get an alolan Vulpix.