Eevee is one of only twenty-seven Pokemon that have a Gigantamax Form in Pokemon Sword & Shield. However, unlike other Gigantamax Forms that are obtained by catching that specific Pokemon from a Max Raid Battle, Gigantamax Eevee is obtained in a special method. In order to receive Gigantamax Eevee, you must have a Let's Go Eevee Save File on the Nintendo Switch you are playing Pokemon Sword or Pokemon Shield on. If you do, you will receive a special Eevee (one that cannot evolve) that will have the ability to be Gigantamaxed during battle.
If you have a Save Data for Let's Go Eevee on the same Nintendo Switch you are playing Pokemon Sword & Shield, you will receive a special Eevee from a man and his children within the Meetup Spot in the Wild Area. This Eevee will come at Level 10 and, as mentioned, has the ability to Gigantamax when in battles that allow it. However, it cannot be a Shiny Pokemon and it cannot evolve.
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