Malamar @ Quick Claw /Choice Scarf
Nature: Adamant/ Jolly
Ability: Contrary
EVs: 252 Atk/ 4 Hp/ 252 Spe
Superpower (Great for Malamar, due to Contrary.)
Foul Play (Better move than Night Slash, send Pokemon with high attack stats to to their grave.)
Psycho Cut (Another reason to call Malamar a psychopatic threat.)
Topsy-Turvy(Malamar sends Belly Drum users to hell.)
This moveset worked great for me in USUM. Superpower boosted his attack to great levels, Foul Play kills strong Pokemon like Gengar, Golurk etc, Psycho Cut has a high critical ratio, paired with Topsy-Turvy, a semmingly innocent move that send set-up like Excadrill, Gallade and may more Pokemon to therapy land. I recommend using the Quick Claw on him, but if you are true competitive players, use the Choice Scarf.