Hey all, quick question. I can't decide what the final move on Hitmonchan's set should be...opinions?

LVL 52 - Adamant Nature (Iron Fist)
Drain Punch
Ice Punch
Bulk Up
Thunderpunch/Mach Punch

I'm thinking Thunderpunch because I'll get coverage against Milotic and other Water types, but on the downside, Thunderpunch could paralyze it and activate Marvel Scale, which would only make things harder. Mach Punch gets STAB and priority, plus it benefits from Iron Fist's boost.

What do you think of this set?