Marley is one of five Trainers who can join with the main character during an event in Pokémon Diamond, Pearl, and Platinum and Brilliant Diamond and Shining Pearl. She first appears in a part of Victory Road only accessible after obtaining the National Pokédex. She is not fond of talking, and although she says that she chooses her words carefully, she is still worried about hurting others with them accidentally. She is fond of Shaymin and wants to inspect the stone tablet at the end of Route 224 in hopes of meeting it. She likes it as it conveys gratitude without the use of words.

Cheryl is one of five Trainers who can join with the main character during an event in Pokémon Diamond, Pearl, and Platinum and Brilliant Diamond and Shining Pearl. Later, she can join the player in competition at Sinnoh's Battle Tower. She first appears in Eterna Forest. She asks the player to join her because she's afraid she might run into Team Galactic. Her Chansey is good at using restoration techniques, but it is not good at offense. When traveling with the player, she also heals their Pokémon completely after each battle.