Last July, Pokémon Go launched and captured the imagination of players worldwide. Now Niantic has revealed their plans for in-game celebrations that includes Pikachus wearing Ash's hat from the animation series and discounts for various items in the shop (incubators, raid passes, max revives, and ultra balls).
As you may know there are also plans for lots of real world events and activities including "Pokémon GO Fest Chicago this July, events hosted at select Unibail-Rodamco locations this August and September in Europe, and Pokémon GO events at the Pikachu Outbreak in Yokohama, Japan".