I'd imagine Alola forms will be available to some extent; I think its more than a coincidence that the Alola forms types where types that were not very common in Kanto...
Ice has Sandshrew and Vulpix, previously all Ice-types where part Water except Jynx.
Steel has Diglett and Sandshrew, previously only Magnemite line (and Steelix)
Ghost has Marowak, previously only Gastly line
Dragon has Exeggutor, previously only Dratini line
Dark has Rattata, Meowth and Grimer (no Pokemon type dark beforehand)