To beat the Mewtwo Tera Raid in Pokémon Scarlet & Violet, the most effective strategy involves using Mew with a Bug or Ghost Tera type and coordinating your moves to lower Mewtwo’s stats, buff your own, and then unleash powerful attacks. Here is a detailed approach:

Key Strategy

• Tera Type: Use Mew with Bug or Ghost Tera type. Bug is preferred for stronger physical moves like Leech Life, while Ghost offers immunity to Mewtwo's Aura Sphere attack

• Moves to Use:
  • Start by lowering Mewtwo’s Special Attack or accuracy with moves like Snarl, Struggle Bug, or Mud-Slap for the first 3-4 turns.
  • Use Swords Dance to boost Mew’s Attack.
  • Terastalize to activate your Tera type and then spam your strongest STAB (Same Type Attack Bonus) move, such as Leech Life (Bug) or Shadow Claw (Ghost)

• Support Moves: Use Amnesia and Bulk Up to tank hits and further boost stats if using a physical attacker build

• Held Item: Equip Silver Powder for increased damage and healing synergy with Leech Life or Shell Bell for healing from damage dealt

• EV Spread: Maximize Attack and Defense EVs; allocate some EVs to Speed to outspeed Mewtwo

• Support Pokémon: NPC allies like Bellibolt (with Discharge and Light Screen) and Mudsdale (with Rock Smash to lower Mewtwo’s Defense) are highly recommended to help tank damage and debuff Mewtwo

• Defensive Buffs: Use Light Screen and Misty or Electric Terrain to reduce damage from Mewtwo’s powerful moves and prevent it from healing with Rest and Chesto Berry

Additional Tips

• Mewtwo will start the raid by shielding and boosting its stats with Calm Mind, so moves like Snarl and Struggle Bug to reduce its offense are crucial

• Avoid Acid Spray as Mewtwo can Calm Mind multiple times, making Acid Spray less effective than Struggle Bug

• The raid can take 25-30 turns or more, so sustain and healing are important

• If playing with friends, coordinate roles so each Mew fills a specific role (support, attacker, debuffer)

By following this strategy—debuffing Mewtwo, buffing Mew, Terastalizing at the right moment, and using strong Bug or Ghost moves—you can efficiently defeat the Mewtwo Tera Raid boss