Pokémon Ultimate Journeys

When a thick fog separates Ash from his traveling companions, he chances into a young Pokémon trainer and her Baltoy on their way to a set of ancient ruins that are said to house the most valuable treasure in the universe. Never one to turn his nose up at the possibility of adventure, Ash volunteers to guide the girl to a mysterious woman he had seen earlier and who, this girl believe, may know more about the ruins.