As he had done in every other region he has traveled, Ash usually catches a Template:Type2 Pokémon early in his journey. Mamepato was caught soon after Ash's arrival in Isshu. In BW002, shortly after a flock of Mamepato had escaped when Ash had failed to capture one of them, he noticed her pecking at the ground, and engaged her in battle. She managed to put up a good fight against Ash's Pikachu, until the Electric Mouse Pokémon finally used Thunderbolt, and caused her to faint. Ash threw a Poké Ball and successfully caught her.
Later on, for the first time, Mamepato was sent out in a effort to save Pikachu and Iris's Kibago from Team Rocket's capture. However, as she was still weak from her last battle, she was quickly defeated by Jessie's Koromori. She was later healed at the Pokémon Center.
Mamepato was occasionally used by Ash to find and track certain Pokémon. She helped Ash find two Darumakka in BW008 and a wild Tsutarja in BW007, playing a dominant role in the Grass Pokémon's capture. At that time, Mamepato had followed Tsutarja throughout from the time she escaped using Leaf Storm. As she witnessed all of Ash's other Pokémon (Mijumaru and Pokabu) fall to the Grass Snake Pokémon's Attract, she volunteers to battle Tsutarja. When Tsutarja attempted to use Attract on Mamepato, Mamepato was unaffected as she was female (a fact of which Ash had been completely unaware of, despite Iris and Dent's assumptions that it was his strategy). After a hard-fought battle, Mamepato weakened Tsutarja just enough for her to be captured by Ash.
In BW010 where she was used by Ash in a 5-on-5 battle against Shooti's Pururiru. She was defeated by a single Water Pulse.