Malamar

Malamar has a relatively unique Psychic/Dark typing which is quite rare among Pokemon. Unfortunately its stats don't support it enough to be viable in the PvE meta as an attacker, and not resisting almost all typings does it no real favors for gym defense either. 

Best PvE Offensive Moveset

• Psycho Cut or Psywave are the Fast Moves of choice, and they benefit from STAB.
• Peck lacks STAB and typing synergy with Malamar's Charge Moves.
• Psybeam isn't a very strong move, but pairs well to fulfill a budget Psychic-type role. 
• Foul Play is the strongest move against a neutral target, but Malamar isn't exactly the best Dark-type attacker. 
• Superpower is meant for PvP.
• Hyper Beam has no use. 

Best PvE Defensive Moveset

• Peck is more favorable for defense, and its typing is useful against Malamar's double weakness to Bug-type Pokemon. 
• Psycho Cut and Psywave have very poor defensive damage output, even with STAB. 
• Psybeam is probably the best Charge Move for defense due to its earlier damage window, making it the hardest to dodge. 
• Foul Play is the next best option, being resisted by Fairy attackers but not by Bug Pokemon.
• Superpower shouldn't be used for defense due to it being resisted by both of Malamar's weaknesses. 
• Hyper Beam is way too slow for defense. 

Psywave is one of the best Fast Attacks in PvP, boasting great energy generation and good damage output. It is extremely flexible due to being a 1-turn move. Psycho Cut is solid and generates even more energy, but it deals far less damage than Psywave. Peck is horrendous

Foul Play is the most well-rounded Charge Move available, sporting solid STAB Dark-type damage output with a moderate energy cost. Superpower is a nice option to Malamar's movepool that gives it some very versatile Fighting-type coverage, though its self-debuff can make it more difficult to use. Psybeam is a poor move that doesn't deal a lot of damage relative to its high energy cost, even with STAB. However, it's the only option available for solid Psychic-type damage. Hyper Beam demands too much energy to be consistently viable.