Mewtwo has previously been Raid Boss in Tier 5 and EX Raids.
Raid
Tier
Boss CP
3,227
Suggested players
2-5
Boss HP
123
Caught CP range
123
Caught CP (boosted)
12 - 32
Minimum IVs
10 / 10 / 10
Standard game images
There is a very low chance that you can get a shiny Mewtwo, which has the following appearance:
Circa
"Mewtwo è stato creato grazie a una manipolazione genetica. Tuttavia, sebbene la scienza sia riuscita a creare un corpo di Pokémon, ha fallito nell’intento di dare a Mewtwo un animo generoso."