Not Bagon. That will fuck up the balance of the whole game. Dragon Pokémon are ALREADY out of balance. 100,000,000 Salamences walking about? No thanks.
Now Ralts or Beldum, I can get behind. Strong, but not changing overall balance if there are many of them out there.
I hope it's Vulpix, personally. I also hope they make it Wurmple, just to fuck with everybody.