However, the Pikachu and Eevee you find in the wild will not Gigantamax. Only special versions of the Pokémon will do so. In order to get these special Gigantamax Eevee and Pikachu, you have to have a save file for Pokémon: Let’s Go, Eevee! or Pikachu! on your Nintendo Switch. You’ll need Let’s Go, Eevee! to get the Eevee and Let’s Go, Pikachu! to get the Pikachu.
Once you have the save file from the game, you have to speak to two NPCs found in the Wild Area train station. The train station is in the Meetup Spot zone of the Wild Area. After seeing you’ve been on an adventure before, they’ll give you the respective Pokémon.
Note that neither of these versions of Eevee or Pikachu can evolve, similarly to the starter Eevee and Pikachu in Let’s Go.
You don’t need to fully complete Let’s Go in order to get the Pokémon, either. You just need a save file from the game, so you can borrow a friend’s copy or rent one to get your fat Pikachu.
Players who have the Isle of Armor expansion can feed Max Soup to any Pikachu or Eevee to turn it into a Gigantamax version as well.