Pokémon GO is celebrating its 10th anniversary with free Timed Research that rewards every player with an encounter with Mewtwo featuring maxed-out stats, a Special Background and the third Mega Level unlocked for Mega Mewtwo Y. The anniversary celebration runs from Aug. 12 at 4 p.m. PDT through Sept. 6 at 11:59 p.m. local time, with players required to complete the Timed Research and claim its rewards before the deadline. The special Mewtwo reward is available globally as part of Pokémon GO’s 10-year celebration, while players who received Mewtwo at the in-person Times Square event on July 9 will receive a different version with different stats and rewards; the Times Square Background will also return at a later date.
Source: Official Pokémon GO blog
Nintendo & Pokémon Blog 