In preparation for Pokémon Go Fest Global on July 13–14, 2024, Niantic is adding special backgrounds to Pokémon that appear during the festivities.
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Special backgrounds are not to be confused with location maps, which are images of cities around the world for Pokémon caught during special live events, such as Go Fest Madrid. They are displayed for everyone, regardless of where you are.
After you catch certain Pokémon during an event in Pokémon Go, usually Legendary or Mythical Pokémon, there's a chance that a background image will appear behind the Pokémon on the event summary page.
Trainers will first get a chance to earn these special backgrounds during the Ultra Space event from July 8-13. All Ultra Beasts in raids during this time period will have a chance to have a background image behind them. The next chance will be from July 13-14 during Go Fest Global 2024, with Necrozma as the primary target.