Replacing the Pokémon Musicals as the alternative Pokémon challenge is PokéStar. PokéStar has a building in which you can participate in Pokémon movies. These movies have you partake in various scenarios to get the best movie. The Icirrus City Gym Leader, Brycen, plays a part in some of the movies
These movies can take up many different scenarios that feature you using your Pokémon and following a script. Initially, you have to use the rental Pokémon dictated by the movies, but once you've finished the scenario, you can enter with your own Pokémon
When you go to make the movies, you walk into an area with a green screen and often face up against a person in a motion capture suit. Here, it often goes into a battle scene where you use your Pokémon against the character in the motion capture suit.
Once in battle, you will get a variety of script options to follow and these options will determine the course of the movie. Once the script is done, the movie is complete and you can watch the outcome. It's currently unknown if there's a ranking system or how the movies are judged.
Below is a list of the movies and how to complete them, courtesy of bluesun