Marley

Marley is a character in Generation IV that first appears in Victory Road after defeating the Elite Four. 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 just wants to tag along. She can later be found in Sinnoh's Battle Tower competing against the player.

Anime
In two of the DP league shows, she was shown transporting a Shaymin to the Gardenia Flower Patch.