Pokémon were the titular characters of the game Pokémon Go. While infiltrating the Tokyo branch of Harmony Shoal, the Twelfth Doctor created a distraction by flooding the downstairs floor with the creatures. (TV: The Return of Doctor Mysterio)
Behind the scenes
Pokémon (short for "Pocket Monster") is a Japanese media franchise that began in 1996 with the launch of the video games on the Gameboy, before becoming a global phenomenon that spawned many more games, an ongoing animated TV series, a trading card game, comics and various other merchandise. The series primarily revolves around the task of capturing the titular monsters and having them battle eachother. Pokémon Go, a free-to-play augmented reality game that allowed players to effectively capture Pokémon in "real life", was launched in 2016.