A great moveset for Hitmonchan:
Ability: Iron Fist
Ice Punch - deals with Ground, Flying, Dragon, and Grass types. More coverage than ThunderPunch, so I highly recommend using Ice Punch rather than ThunderPunch.
Bullet Punch - deals with Rock and Fairy Types. Priority move as well.
Drain Punch - STAB, recovers HP, paired with Iron Fist ability, need I say more?
Focus Punch or Sky Uppercut - using a good strategy, I'd choose Focus Punch, but if you're wary about using it, choose Sky Uppercut instead.
This is an up-to-date Hitmonchan moveset, a couple weeks after the release of X and Y . It's very effective. (y)