Mewtwo

Mewtwo is a Psychic-type Legendary Pokémon from the Kanto region. It doesn't evolve from or into any other Pokémon. It is only available for capture when defeated as a Raid Boss during an EX Raid Battle.

Trivia

 * On August, 2017, one day before the Pokémon GO Stadium event, a shiny variant was added to the game files, along with stat changes.
 * Mewtwo was confirmed as a Raid Boss the following day.
 * Trainers who defeated a Mewtwo Raid Boss at Pokémon GO Stadium received over 50 Premier Balls and an increased capture rate.
 * Mewtwo appeared as Raid Boss also in Pokémon GO Park event.
 * CP of Mewtwo with perfect IVs at level 20 is 2,275 and at level 40 is 3,982.
 * That makes it the highest maximum CP Pokémon from Kanto region.
 * Mewtwo has the highest Attack statistic in the game.
 * Mewtwo will only be able to learn Hyper Beam and Shadow Ball up until September 20 at 1 p.m. PDT.
 * Starting on September 20, 2018, Mewtwo will be available from Raid Battles until October 23, 2018.
 * On September 20, 2018, Mewtwo will no longer be available from EX Raid Battles and will be replaced with Deoxys.
 * On September 20, 2018, Mewtwo will no longer be available from EX Raid Battles and will be replaced with Deoxys.