Well, the general ruling is that attacks that a Pokemon doesn't have but can just "use" don't actually belong to the Pokemon, anyway (Mew EX and Round, for example.) There already has been a ruling that Mew EX does not get the benefit of King's Song if it uses a Poliwhirl/Polywag/Poliwrath attack. I would be very surprised if a ruling came forth that said you could ignore the colorless.