My heracross always seems to own PO with this set
That bug's got some Moxie
Heracross@Choice Scarf
Admant nature
252 Attack/252 Speed/4 HP
Ability: Moxie
~Close Combat
~Stone Edge

The scarf takes care of the speed. It amps it up so that it can outrun most sweepers. Close combat takes care of Rocks, Steels, Darks, Normals and more importantly that annoying Grass/Steel. Stone edge takes care of any Flying types that want to have Heracross for lunch. Megahorn takes care of Psychics, one such as espeon. Earthquake covers fire types and everything else. All you really need is one, well timed, close combat, and Moxie will take care of the rest.