Millefeui

Millefeui is a profession PokéPuff chef who Serena met during a PokéPuff Contest. When there, Millefeui noticed Serena's crush on Ash and used it to distract her showing she has a devious side. She even mentioned that if Serena took too long, she'd steal Ash from her, and often teases Serena about her crush. She later showed up participating in a Pokémon Showcase but lost to Serena.

(Source: serebii.net)