Walrein was sent out, along with Rocky's Quagsire, in a Double Battle against Ash's Grovyle and Pikachu. Pikachu launched its Thunderbolt on Walrein, but Quagsire stood in his path and took the hit. Walrein retaliated with Ice Ball, though Pikachu and Grovyle avoided the attack. Just as Grovyle was to use Leaf Blade on Quagsire and Pikachu to use Iron Tail on Walrein, Quagsire and Walrein swapped sides. This caused Pikachu and Grovyle to bump into each other and their attacks failed. Thus, Walrein launched another Ice Ball and hit Pikachu. After hiding behind a rock from Grovyle's Bullet Seed, Walrein launched a third Ice Ball, which hit Pikachu and Grovyle, who tried to stop the attack. Pikachu and Grovyle dodged Walrein's fourth Ice Ball, while Ash noted Walrein needed time to launch the ball. In a final attack, Pikachu used Thunderbolt on Walrein; Quagsire stood in Walrein's defense and took no damage from the attack. However, immediately after, Grovyle used Leaf Blade and defeated Quagsire, while Pikachu jumped and defeated Walrein with Thunder.