In Pokémon Scarlet and Violet, you can change your Pokémon’s names no matter where you are. If you accidentally made a typo, had a change of heart, or maybe you just accidentally button mashed and skipped the nicknaming screen, don’t worry. You can fix and add a new name immediately.
To do this, open your menu by pressing X, select the Pokémon whose name you want to change, and select “Check summary.” On this screen, you should be able to press X to change their nickname.
This is a departure from previous mainline Pokémon games, where you had to go to a “name rater” NPC, who would tell you that whatever nickname your Pokémon had wasn’t that good. They would then prompt you to rename your Pokémon.
This does mimic Pokémon Legends: Arceus’ system for name changing, though this involves going through a few more menus, so it’s easy to miss.