There is no Move Tutor or Move Relearner in Pokémon Scarlet and Pokémon Violet. Game Freak has chosen to streamline how your pocket monsters can relearn old moves as you adventure across the Paldea region.
Whether you skip learning a move by accident or on purpose, the way to relearn old moves is to open the in-game menu (X Button), before selecting the Pokémon to then choose the option Check Summary.
From here, press the right button to be able to view your Pokémon’s Moves and Stats screen, where you can hit the A Button to select the Change Moves option. This will then present you with the chance to “Remember Moves,” “Forget a Move” or “Use TMs to learn Moves.”
The “Remember Moves” option will list the moves that your Pokémon has access to based on their current level, but does not let you see at which level they will learn moves in the future. Simply select the move that you want your Pokémon to remember, and you will then be asked to confirm the move that it should replace.
Pokémon Scarlet and Pokémon Violet are now available at retail and digitally on the Nintendo eShop for Nintendo Switch worldwide.