OK... you go to cerulean cave and go far throughout the maze and you find it... bring it's HP low and throw a ultra ball OR you throw ( waste) a master ball from the start of the match and... boom you caught yourself a MEWTWO! Good luck with the pokedex then...

Hehe- wait it's the overseer?! I thought it was mewtwo... well don't care about all what I said except if you wanna catch mewtwo but you dunno how...

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