The code DREAMB1GPC3 can be entered for a Dream Ball in the Mystery Gift menu found in the main menu of the game. Once there, simply select “Get with Code/Password” and enter the provided code to secure your loot. The code will only be available to redeem until April 12.
A Dream Ball is one of the rarest items in the game since it’s only available at a single point during the campaign and if missed there’s no other way to obtain it other than a Mystery Gift. This ball is effective when used on Pokémon who are sleeping, making it much easier to capture them.