After completing Round 1 or Round 2 of all Stadium cups and the Gym Leader Castle, Mewtwo appears in the sky over the stadium. Selecting Mewtwo allows the player to engage in a battle with it. Defeating Mewtwo's Round 1 version is the trigger to unlock Round 2 for all tournaments and challenges, and defeating its Round 2 version unlocks hidden stickers in the Gallery.
In the original release, the player can choose to use either a team selected from rental Pokémon, a team consisting of Pokémon from a connected copy of Red, Green, Blue, or Yellow, or a mix of both. In the Nintendo Switch rerelease, only rental Pokémon can be used. The rentals the player can select from are identical to those of the Prime Cup.
The player is allowed to use all six Pokémon in their team to take down Mewtwo.
The player's final Pokémon cannot use Selfdestruct or Explosion to defeat Mewtwo.
| Pokémon | Level | Moves | HP | Atk | Def | Spe | Spc | ||||||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
![]() |
Mewtwo | 100 | Psychic | Rest | Thunderbolt | Blizzard | 385 | 286 | 248 | 328 | 376 | ||||||||
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16 PP |
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16 PP |
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24 PP |
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8 PP | ||||||||
This version of Mewtwo has perfect DVs and maxed Stat Exp. in every stat.
| Pokémon | Level | Moves | HP | Atk | Def | Spe | Spc | ||||||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
![]() |
Mewtwo | 100 | Psychic | Thunderbolt | Rest | Amnesia | 415 | 318 | 278 | 358 | 406 | ||||||||
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16 PP |
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24 PP |
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10 PP |
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20 PP | ||||||||