I have tons of HA Pokemon, including Extreme Speed Dratini's.
For Gen 6, I can breed with their HA, Minccino, Bulbasaur, Shelmet, Snivy, Chespin, Eevee, Chikorita, Cyndaquil, Torchic, Chimchar, Tepig, Squirtle, Totodile, Frokie, Poliwag, Swinub, Pikachu, Bunnelby, Roggenrola, Fletchling...