Obscure 2000s cartoon – friend turns green and evil, pink-haired girl

Body:

Trying to find a cartoon I watched as a kid (~2007–2008):

• Late 90s–early 2000s Cartoon Network/Nickelodeon vibe (same era as Ed, Edd n Eddy / Foster’s Home for Imaginary Friends).
• Friend group of kids/teens, stylized like Codename: Kids Next Door.
• In one episode, one kid turns green with energy and becomes evil, but stays human.
• A girl with pink hair is next to him.
• Possibly in a mall or city.
• Only one episode is memorable—nothing recurring.

I’ve ruled out Danny Phantom, Powerpuff Girls, KND, 6teen, and Totally Spies!.
Does anyone know what show/episode this is?