Mewtwo is a playable character in the fighting video game, M.U.G.E.N Trilogy. It was confirmed along with the other characters from Super Smash Bros. Melee on February 1, 2015. Keiji Fujiwara provides the role for Mewtwo in this fighting game, using voice clips borrowed from Super Smash Bros. 4.
Mewtwo is Pokémon #150 in the Generation I Pokédex, the final Pokémon in the list when not counting the generally unobtainable Mew which is #151 in the Pokédex. It is a clone of Mew that has been altered by unscrupulous scientists in order to increase its power and make it solely oriented for battling. As a result, it retains Mew's feline features, but instead sports a gray and purple coloration, a large, humanoid physique and even stronger psychic abilities, due to the alterations to its genetic source material. The Pokédex also categorizes Mewtwo as the "Genetic Pokémon".
Mewtwo's mentality also vastly differs from Mew's: the last journal entry written by a researcher who oversaw Mewtwo's origin mentions that its viciousness lead to it violently escaping captivity, while Pokédex entries in Generations I and II establish that it thinks only of defeating its opponents and supplements this intention with a propensity for focusing its powers and resting in undiscovered areas.
How to Unlock
Use Mewtwo's Super Smash Bros. amiibo or scan Mewtwo's AR Icon from the M.U.G.E.N Trilogy website.