Cheryl

Cheryl is a character that first appears in Eterna Forest. She can join the player during an event in Pokémon Diamond, Pearl, and Platinum. She asks the player to escort her to the exit because she's afraid she might run into Team Galactic. She can later be found in Sinnoh's Battle Tower competing against the player. All of her Pokémon have high amounts of HP.

In the anime
Cheryl made her debut in Some Enchanted Sweetning where she was looking for the Amber Castle.