Competitive Guide: Navighast

[Dragonstrike]

Okay, so there might be a precedent for Ditto not passing egg moves in the main series after all: in Gen 2, there's a Glitch that allows a Transformed pokemon to learn any move permanently, overwriting Transform.  It's a little vague, but this thread on Serebii seems to suggest that Ditto can't pass on moves it learns with that glitch even if the egg moves are valid for the offspring (otherwise, it'd be possible to get Staryu with their unobtainable egg moves from G/S, for example).

It might be because the gen 2-5 games are only programmed to let male pokemon pass down egg moves.  And starting in gen 6, that was changed to male and female, but still didn't include genderless pokemon.