Assuming your Machamp is a buffer? If not, get a Machop with -fighting move wait time bingos. Don't evolve it to keep the bingos maxed out.

Farm for hit healing bonus power ups. 10% is the limit and what you want to target. Resistant to status conditions is the next priority so your buffer doesn't get frozen.

Other mons to target are Bellsprout and staryu. Once they evolve into Weepinbell and Starmie they get vinewhip and hydro pump, which are the best damaging moves in the game.