After you have created the movie for the first time, you have the ability to enter the movies with your own Pokémon. However, if you deviate from the script, say things out of character but don't fail the mission, then you will get the "Strange" ending of the movies. An example would be defeating Brycenman's Pokémon within the "Brycenman Strikes Back" movie.
If you do this successfully, your Pokémon will become a star, and will have a special intro animation that will show a star bouncing upwards as the Pokémon enters battle. This is a very rare sight for now so be sure to accomplish the movie missions in your own way. If you then send these Pokémon out again in movies, you will gain more revenue.
If you keep on sending that Pokemon out, your movies will gain more money, basically.