I think Crystal Onix should be in the game. A real rare Onix, with the Dry Skin ability and the color showed in the anime, but with no changes in the typing.

if this pokemon was in the original pokemon games too then i agree :)

Well maybe suggest it as Mini Boss :y:

Actually, crystal onix is already part of the game, via certain method but its not for players as its just a bug. Maybe they will put it correctly to be accessible by players.