Pokémon Day 2017

Pokémon Day in 2017 was the first Pokémon Day event in Pokémon GO.

Features
To celebrate Pokémon Day, any Pikachu that were encountered in the wild wore a festive party hat. Any Pikachu captured during the event keeps its hat forever and every Raichu evolved from Pikachu with such hat have the same hat as well.