Miyuki

Wilhomena is a character of the day who appeared in For Crying Out Loud. She is a rich young woman from Johto who lost her crybaby Marill, which Misty found and tried to keep for herself.

Like her Marill, Wilhomena was spoiled and prone to crying herself. However, after Misty, Pikachu and Wilhomena's Marill were separated from the rest of the group, while searching for them with Ash, Brock and Togepi, Wilhomena seemed to develop a certain affection for Brock, much to the surprise of Ash and Togepi. After she and her Marill were reunited, she returned home, expressing an interest in meeting Brock once again.

(Source: Bulbapedia)