I'm trying to breed a Rattata that knows Reversal, but I have no idea how to get the move over to that group. Can I do it, or must I use Smeargle? And if I have to use Smeargle, how would I get it onto him?
Sketch would be the way. Try to sketch Heracross, Hitmonlee or Kangaskhan at fairly high levels (Heracross: over Lv41, Hitmonlee: over Lv51, Kangaskhan: over Lv49). Those three know Reversal naturally.