Darkrai-Garbodor, Yveltal-Garbodor - maybe they do have favorable match-ups, but in my experience I didn't have trouble with them
Volcanion - I have more then 85% win when facing mirror deck, maybe I'm just lucky :)
Mewtwo-Garbodor - yep, you are right about this one, I'm roughly on 50-50 with...