Well, I used my Crobat in a pokestar studio movie, and since a big star appears every time I send him out in battle, was that was supposed to happen? Because that looks really cool!
It's because your Crobat is a movie star.
In Black 2 & White 2, there is one final animation added. If you use your Pokémon within the PokéStar movies and deviate from the script, while still accomplishing the mission, your Pokémon will become a star and will be given this animation. Upon entry of battle, a star will shoot up from the Pokémon and bounce back down.
Source
Hope I helped!
