Pokémon Adventures: Diamond and Pearl/Platinum Vol 1

From the VIZ Media edition

Pokemon trainers Pearl and Diamond are starstruck! Their lifelong dream is to floor an audience with their Pokemon comedy act. So how do they wind up as bodyguards to a pampered little rich girl on a quest to reach the peak of Mr. Coronet…?! Come along and join in the thrills and laughs as Pokemon Adventures continues! Plus, meet Starly, Bidoof, Luxio, Combee, Bronzor, Rotom and many more sinnoh Pokemon friends!

Source: Anime News Network Encyclopedia