Mewtwo is a Psychic-type Pokémon, which makes it weak against Bug, Dark, and Ghost-type moves. Therefore, the best Pokémon to use against Mewtwo in a raid scenario are those of these types. Some recommended Pokémon and moves to use when battling against Mewtwo include:

• Gengar: Lick, Shadow Ball
• Houndoom: Snarl, Foul Play
• Tyranitar: Bite, Crunch
• Weavile: Snarl, Foul Play
• Chandelure: Hex, Shadow Ball
• Yveltal: Snarl, Dark Pulse

. Its worth noting that Mewtwo is stronger against Fighting-type enemies and other Psychic types, so its best to avoid using these types against it.