Me and my brother are doing mono-type battles. Unfortunately for him, besides the Pokemon that he actually uses on his team, he hasn't cared enough to give his Pokemon good movesets. Our first battle will be mono-dark. Here are his Pokemon and their moves. Don't suggest improvements for movesets (comment on them in the question if you want.) Just choose six Pokemon.
Umbreon: Toxic, Moonlight, Taunt, Snatch
Migtyena: Fire Fang, Crunch, Ice Fang, Thunder Fang
Absol: Psycho Cut, Slash, Night Slash, Shadow Claw
Darkrai: Dark Void, Thunderbolt, Dream Eater, Nightmare
Houndoom: Howl, Roar, Flamethrower, Crunch
Sableye: Foresight, Dig, Mean Look, Shadow Ball
Honchkrow: Torment, Dark Pulse, Sky Attack, Taunt
Weavile: Night Slash, Dark Pulse, Metal Claw, Icy Wind
Tyranitar: Surf, Earthquake, Thunder Fang, Dragon Claw
Shiftry: Whirlwind, Icy Wind, Extrasensory, Razor Leaf
Sharpedo: Poison Jab, Aqua Jet, Crunch, Earthquake
Cacturne: Needle Arm, Sandstorm, Destiny Bond, Cotton Spore
Crawdaunt: Vicegrip, Guillotine, Harden, Crabhammer
Skuntank: Flamethrower, Explosion, Fire Blast, Poison Gas
Spiritomb: Hypnosis, Dream Eater, Will-o-wisp, Ominus Wind
Drapion: Fire Fang, Thunder Fang, Ice Fang, Poison Fang