Both Zacian and Mega Rayquaza are strong, but they are no match for the original Uber: Mewtwo. Mewtwo takes everything broken about Gen 1 and abuses the hell out of every one of them. Critical hits being based on speed? Mewtwo has one of the best Crit Rates with 23%! Psychic teypes having no Steel or dark Types to work around. Yep, Mewtwo is definitely a Psychic type. Special Attack and Special Defense being oe stat?! Mewtwo has the highest Special stat in the game, making it mind-meltingly powerful and also mind-meltingly bulky. In Gen 1, you do not counter Mewtwo. You simply hope that it doesn't take out too much of your team before hoping you beat it with your own Mewtwo.