Alolan Mudkip
Dragon/Fairy Type
Whatever abilty Zygarde has, so there are more forms of mudkip
I would have wanted a Psyduck and Golduck that was actually part-Psychic and having psychic powers affect their appearance. That was definitely a missed opportunity.
With the coral reefs dying off, I would love to see Ghost/Rock Corsola. It's ability could be Cursed Body or Solid Rock.
The water-type Arcanine we were promised in the leaks, man. That'd be awesome to see.
I'm actually rather upset to this day that Water-type Alolan Arcanine isn't a thing. Not only would it have been awesome, but it would've made sense as its counterpart has an Alola form. Why leave Arcanine in the dust, Game Freak?
It would've been nice to see Butterfree get an Alola form, too. Although Beedril doesn't have one, it has a Mega, so it would've been neat to see Butterfree get at least something, but nope. :c