Iron Fist is only a 20% boost, but it's the most feasible Ability to run for a SubPunch set. Sheer Force would only boost coverage moves and Guts requires you to sacrifice survivability, which obviously isn't an option with a Sub set. And Mach Punch is a guaranteed boost for virtually any move that Conkeldurr would move except Payback.
FaceFaceFace: "Genesect is like the Terminator. Scary when he's coming after you, absolutely lovely with ridiculous punch-lines when he's on your side."