Your Pokémon username is how other players know you in the game. Changing it lets you update how you appear to friends, in battles, and across your account. This category covers the steps to change your username, what happens to your existing data when you do, and what to expect after the change takes effect.
The articles here answer questions like how to find the username change option in your account settings, whether your progress and items stay with you after a change, how long the change takes to show up in the game, and what restrictions might explore to how often you can make changes.