Just an fyi, if you find a Ralts with the ability Synchrnoise and a Hasty Nature, all the wild Pokemon you see will be Hasty if that Ralts is in the first of your party (dead or alive).
And that Ditto would just affect the chances of the kid Pokemon on getting 0 Speed IVs if you have a Destiny Knot attached to it or its partner. 0 Speed Dittos are good for breeding with: Ferroseed, Foretress, and Honedge.