The movie has now been officially announced and will be out July 12, 2019 in Japan.
There is no word yet on an international release and an official trailer has yet to be released.
Text appeared on the screen, stating that the legend was back. Bubbles started floating up, and a voice said, “What is this place? Who am I?” Then, there was a close up of Mewtwo opening his eyes. (Above is the first official teaser image for the movie.)
The logo flashed on the screen, reading 劇場版ポケットモンスター ミュウツーの逆襲 Evolution or Pocket Monsters The Movie Mewtwo Strikes Back Evolution.
Is this a reboot? A reworking? What?
According to Comic Natalie, it is still unclear how Mewtwo Strikes Back Evolution is connected to Pocket Monsters the Movie: Mewtwo Strikes Back, the first Pokémon animated film that first premiered back in 1998.