Pikachu Parties in Pokémon GO!
Keep your eye out for a special Pikachu wearing a party hat to celebrate Pokémon Day!
February 21, 2017
Pikachu is ready to lead the Pokémon Day celebration in Pokémon GO. From February 26 at 1:00 p.m. PST to March 6 at 1:00 p.m. PST, any Pikachu you encounter in the wild will be wearing a festive party hat! The Pikachu you catch during that time will keep its party hat forever, so be sure to look for this special Pikachu during its short time in the wild.
— Pokémon News
…Wanna play? Buy a 3DS.
That being said, click on Pokémon Go for everything you need to know about the game. 😀