Pokémon the Movie: Monsters Unleashed

Scooby and his pals are invited to the opening of the Coolsonian Criminology Museum, a museum dedicated to the gang's long history of monster hunts and ghost stoppings, and they invited Ash, Serena, and Pikachu as special guests of honor.

However, an evil masked figure shows up and crashes the opening party. Then, the gang's reputation is on the line. With the gang's reputation on the line and more and more of the gang's old monsters and foes coming to life, will they be able to stop this craziness and save the world?

I own neither Pokémon or Scooby-Doo, this is just a neat little crossover adaptation to celebrate the recent 18th anniversary of the movie this story adapts