On Nintendo Switch, you can continue playing Pokémon Champions with the same game account by launching the game using a user profile linked to the same Nintendo Account you previously used.
Mobile game data cannot be recovered if you delete the app before linking an account. Additionally, if you delete your game data via the “Delete Account” option, your data cannot be restored.
However, if you have linked your data to a Google Account, Apple Account, or Nintendo Account, you can continue playing with your existing Pokémon Champions data by logging into the game with that same account.