Rimu

Lyn is a character of the day who appeared in A Jolting Switcheroo!.

She and her older sister Lena were resting at the same Pokémon Center as Ash and his friends. Unbeknownst to any of them, Lyn's near-identical bag, which contained a Pichu she had been caring for, was accidentally switched with Bonnie's bag, which contained Dedenne. As she and Lena left and were walking down the street, Lyn noticed Dedenne was in her bag instead of Pichu. Worried, she quickly ran off to find Pichu while Lena was busy talking to a friend.

(Source: Bulbapedia)