I was thinking of breeding Counter into a Scyther,but will it OHKO a high Defence Pokemon like Steelix or Aggron?even after a couple of Swords Dances?
Sword Dance has nothing to do with Counter - It deals twice the damage Scyter took. It is about HP and only HP. Attack does damage (AttXDef) - lost of HP. Then, Countering it would deal 2x los of HP