I love Copperajah. It's a really cool Pokemon with not a bad shiny, either. Here's what I would go for:
Copperajah @ Choice Band/Life Orb
Ability: Sheer Force/Heavy Metal
EVs: 252 HP / 252 Atk / 4 Def
- Iron Head/Heavy Slam
- Rock Slide
- Stealth Rock/Power Whip
If you're running Heavy Slam, go for Heavy Metal. If you're running Iron Head, stick with Sheer Force. Rock Slide I use for double battles in the VGC 2020 format just to have a rock type move that can hurt flying types. I'll run Power Whip for coverage against Pokemon weak to, say, water. If you're running Stealth Rock, use a Life Orb instead of a Choice Band. It does the same thing almost without being locked into a move.
I'm new to all this making movesets stuff since I've been a causal player for all the time I've been a Pokemon fan, so if anyone has any suggestions they'd like to make to improve my Copperajah set, that would be perfect.
I hope this works!