Pokemon Diamond & Pearl Atsumare! Pokemon Hoshi Matsuri

Satoshi, a boy who aims to be the world's best Pokemon Master, his partner Pikachu, and his traveling companions Hikari and Takeshi. Since today is the "Pokemon Star Festival" various Pokemon have gathered around, one after the other, and so Satoshi and his friends decide to join in!! The shady hosts of the festival are getting everyone fired up, but it seems like our heroes have seen them before? As everyone is enjoying events like the Pokemon Quiz and nighttime star gazing, the Pokemon start to disappear one by one. Even Satoshi's Pikachu goes missing! Can Satoshi and Pikachu make it out of there safely?!

(Source: Dogasu's Backpack)