Malamar has the ability Infiltrator, a looked over ability due to the Superpower Contrary combo used with it. I think that Infiltrator Malamar has some good use in OU. Here is the strategy.
Malamar
EV: ATK 200/ SPE 252/ DEF 56/
Ability: Infiltrator
Nature: Jolly
Item: Choice Scarf
Move 1: Throat Chop
Move 2: Psycho Cut
Move 3: Retaliate
Move 4: Liquidation
Psycho Cut and Throat Chop are stab moves and in OU, Throat Chop can hinder Pixilate Hyper Voice Sylveon on a switch-in, while also being able to outspeed easily if you can predict the move. Malamar suffers from Bug-Types heavily, such as U-turners, and Frosmoth like Pokemon due to Malamars poor Defenses. Liquidation is used as coverage and can lower the defenses of opposing Pokemon and pressure Fire, Rock and Ground types like Excadrill, Rotom-H, and Tyranitar along with Coalossal and Centiskorch. Retaliate is a 70 base power move with the special ability to double in power if a teammate fainted last turn, giving Malamar the ability to be a revenge killer against some Pokemon with the Speed, Nature, and Scarf giving it a large boost from a relatively bad 73 base speed. The DEF EVs are there as a safety to survive Priority attacks like an Ice Shard or Quick Attack at low health.
Malamar
EV: ATK 200/ SPE 252/ DEF 56/
Ability: Infiltrator
Nature: Jolly
Item: Choice Scarf
Move 1: Throat Chop
Move 2: Psycho Cut
Move 3: Retaliate
Move 4: Liquidation
Psycho Cut and Throat Chop are stab moves and in OU, Throat Chop can hinder Pixilate Hyper Voice Sylveon on a switch-in, while also being able to outspeed easily if you can predict the move. Malamar suffers from Bug-Types heavily, such as U-turners, and Frosmoth like Pokemon due to Malamars poor Defenses. Liquidation is used as coverage and can lower the defenses of opposing Pokemon and pressure Fire, Rock and Ground types like Excadrill, Rotom-H, and Tyranitar along with Coalossal and Centiskorch. Retaliate is a 70 base power move with the special ability to double in power if a teammate fainted last turn, giving Malamar the ability to be a revenge killer against some Pokemon with the Speed, Nature, and Scarf giving it a large boost from a relatively bad 73 base speed. The DEF EVs are there as a safety to survive Priority attacks like an Ice Shard or Quick Attack at low health.