Traversing through Reflection Cave, Ash & co. are checking out the marvels of the cave's reflective structure when Pikachu is taken from Ash by a strange version of Ash. Ash instinctively follows his doppelganger and ends up in a mirror world, where Serena is determined, Clemont is athletic and Bonnie is very "lady-like", all the opposite of the friends he knows. Will Ash be able to find Pikachu and return to his world?

As they near Shalour City, Ash & Co. learn of a Pokémon Summer Camp being held by Professor Sycamore. In this camp, the trainers compete with each other in various activities, and get scored based on it with the top trainers entering the special Hall of Fame. When at the camp, they meet a trio of trainers, Shauna Trevor & Tierno who have Bulbasaur, Charmander and Squirtle as their partner Pokémon. A rivalry quickly develops between the seven and the Summer Camp begins...