Since this is a weather dependant move, I really think Castform should learn it. Maybe make it its signature move. If you're not doing that, maybe Flying types with strong wings or pretty much anyone who learns Hurricane.
Probably not Castform, since I don't plan to give it a prominent appearance in the game (though that is subject to change, of course). The Hurricane thing would work, though. Although Tornado is about even with Hurricane (not in terms of BP, but in terms of overall power), so it would have to either replace Hurricane entirely or come somewhat close to it.