You will need to purchase the Expansion Pass that matches the version of the game you own.
If you have Pokémon Sword, you will need to purchase the Pokémon Sword Expansion Pass, while if you have Pokémon Shield, you will need to purchase the Pokémon Shield Expansion Pass.
Each Expansion Pass is only compatible with the game version of the same name.
You will be unable to play the additional content if you get the wrong Expansion Pass, so be careful!
Purchase in Nintendo eShop
The Pokémon Sword Expansion Pass and Pokémon Shield Expansion Pass will both be available in Nintendo eShop. You’ll be able to check the purchase page of the correct Expansion Pass for your game version by selecting the Expansion Pass notice displayed in the menu screen of Pokémon Sword and Pokémon Shield.
Note: When purchasing the Expansion Pass from the in-game option, you will need to have the latest version of Pokémon Sword or Pokémon Shield installed.
Purchase a download card or download code
Download cards and download codes for the Expansion Pass will be available at participating retailers. These download cards and download codes are the same for both the Pokémon Sword Expansion Pass and the Pokémon Shield Expansion Pass, and you’ll choose which Expansion Pass you want when you enter the code in Nintendo eShop. Please make sure to select the version that is compatible with your game.