Caught a Shiny Mewtwo today! Joined a Raid Battle in Toshima, Tokyo — and the catch screen flagged it shiny. CP 3658, dropped in an Ultra Ball. The green tail and green underbelly are the unmistakable shiny markers (normal Mewtwo is purple in those spots).
Same neighbourhood as the Groudon catch from earlier today and the Ikebukuro Pokémon GO hotspot I wrote about — raid lobbies fill to 20 trainers in seconds here, so legendary catches stack up fast.