What I use on Showdown at least is the following:
Kecleon @ Assault Vest
Ability: Protean
EVs: 4 HP / 252 Atk / 252 Def
Adamant Nature
- Shadow Sneak
- Power-Up Punch
- Aqua Tail
- Knock Off
I'm not sure if all those moves are available in game but try get them, STAB Knock Off is brutal. Shadow Sneak is vital to piss off Fighting types and for close calls in general. Power-up Punch is just a nice move to have in my opinion and Aqua Tail is for some nice beefy damage compared to the other moves and still more coverage.
I'm hoping to breed a Kecleon like this in game for some shenanigans myself.
