>>42695079Well, at least in Gen 7, he gets the elemental punches. So assuming those aren't taken away they give you some options. You're probably going with Ice Punch and Draining Punch by default. Then maybe Zen Headbutt/Heavy Slam/EQ for the third slot. Doubt he's keeping Knock Off. This is assuming an offense-heavy set that combines with an ability nullifying partner, like the thread premise-- otherwise you're probably doing the ol' T-Wave Substitute stall shit.
Now here's the problem, and again, this is based off Gen 7's movesets-- Regigigas has the following STAB attacks not counting Return/Frustration and Hidden Power: Crush Grip, Dizzy Punch, Giga Impact, Hyper Beam, Snore (no Rest lol), and Facade. Which really narrows you down to Dizzy or Facade for a reliable attack, and those are both 70 BP.