The Pokémon 25th anniversary, officially branded as Pokémon25, was an ongoing celebration that went for the entire year of 2021 in commemoration of the twenty-fifth anniversary of the Pokémon franchise, which began with the original Japanese release of Pocket Monsters Red and Green for the Game Boy on February 27, 1996. The anniversary saw the announcements of Pokémon Brilliant Diamond, Pokémon Shining Pearl and Pokémon Legends: Arceus.
Learn more about the anniversary