Elle

Madison is a character of the day who appeared in The Kecleon Caper (EP207).

Madison and her sister Alexa are a pair of rich young sisters who are traveling the world in the massive "Leviathan Two", a luxury blimp. They dress in fur coats and each have a Kecleon. Brock helped their Kecleon recover from motion sickness.

(Source: Bulbapedia)