The first Pokémon Appreciation Day for Pokémon GO takes place on October 22nd, 2018 and Niantic would like players to post their pictures of Bidoof on social media.
You’ve got it, Trainers! We’re kicking off our first Pokémon Appreciation Day by featuring the Plump Mouse Pokémon, Bidoof! Show us your love for Bidoof by posting your favorite AR photos of it with #BidoofDay, and we’ll share some of our favorites!
Source:
https://twitter.com/PokemonGoApp/status/1054439775200010240