Pokémon Adventures: Diamond and Pearl/Platinum Vol 6

From the VIZ Media edition

Platinum gets a new Pokemon, and an old Pokemon friend gets a Trainer! Then, our trio divide and conquer. While Platinum skis the slopes and pursues her Glacier Badge, Pearl investigates Team Galactic, and Diamond stumbles upon a luxurious mansion staffed by a stuffy butler. Where could Diamond be...?! Meanwhile, what is Team Galactic member Mars doing with that mysterious flying camera...? Plus, meet Snover, Froslass, Lickilicky, Yanmega and many more Sinnoh Pokemon friends!

Source: Anime News Network Encyclopedia