How to Get Mewtwo in Pokémon Games
- 1). Defeat Giovanni, the leader of Team Rocket, on the 11th floor of the Silph Co. headquarters in Saffron City. The hostage, the president of Silph Co., will give you the Master Ball as your reward for freeing him.
- 2). Win all of your gym badges, then defeat the Elite Four located outside Viridian City.
- 3). Travel to the cave outside Cerulean City. You must use Surf to get there. The guardian to the cave will only let you enter if you have defeated the Elite Four.
- 4). Travel through the maze inside the cave. When you reach Mewtwo at the end, battle it, but instead of trying to defeat it by reducing its hit points, use your Master Ball, which is a one-hit ball capable of capturing any Pokémon.