Location: Knowhere.
KO.
Batch 1: regular Jean Grey.
Round 1: regular Mewtwo.
Round 2: Mega Mewtwo X.
Round 3: Mega Mewtwo Y.
Batch 2: Phoenix.
Same rounds as above.
Who would win and why?
Links:
https://vsbattles.fandom.com/wiki/Mewtwo
https://m.bulbapedia.bulbagarden.net/wiki/Mewtwo_(Pok%C3%A9mon)