The Pokémon Summer Camp competition is coming to a close with both Ash & Tierno's teams at the top of the rankings. For the final assessment, a special Team Battle is to be held. This is where the six trainers face off against eachother at the same time. Before the battle, they all head to the Pokémon Center to make sure their Pokémon are in top-form. However, as Team Rocket have been posing as chefs in the camp, their plan finally comes to fruition and they capture many trainer's Pokémon, including Tierno's Squirtle. Will they manage to retrieve the Pokémon and, when it comes to the battle, who will win and join the Summer Camp Hall of Fame?

When the Mythical Pokémon Diancie cannot figure out how to make a new Heart Diamond to save her kingdom of Carbink subjects, she seeks out the Legendary Life Pokémon Xerneas for help, meeting Ash, Serena, Clemont, and Bonnie on the way, as they help her escape a group of jewel thieves and the unintentional awakening of the Legendary Destruction Pokémon Yveltal.