Cameron is a Pokémon Trainer that planned to participate in the Pokémon World Tournament Junior Cup in Kagome Town but he arrived too late to participate in the competition. Ash Ketchum and his friends informed him that it had just ended. While parting ways with Dawn, Cameron arrived at the boat launch obviously trying to go to the Johto region but he just missed the flight.
Cameron met Marlon as he was on top of his Wailord as it came close to the beachline where Ash Ketchum and Cameron were. Before the gum match, Marlon told Cameron that he'd stop him with his deep love for the sea. Marlon instructed that the Gym battles at the Seigaiha Gym are two Pokémon apiece and whoever defeats both first wins. Initially Cameron thought he did well in the battle and was going to have an easy victory in the match by quickly defeating Marlon's Jellicent but Marlon's tactic was revealed when Marlon's Jellicent Ability Cursed Body disabled Cameron's FerrothornThunderbolt.
Marlon's Mantine tried to turn the tie of the battle to Marlon favor but Cameron's Samurott was able to hold its own in the water and give the match victory to Cameron. Marlon was actually quite impress with Cameron as he was able to make the special field his own.
The final match up was between Cameron's Riolu and Bianca's Emboar. It was pretty one sided as Bianca's Emboar was already pretty tired and it couldn't land any hits. It was able to grab its foot at one point and throw it hard but Cameron's Riolu landed on the ground upright. Cameron's Riolu defeated Bianca's Emboar and as a result Bianca was eliminated from the Isshu League tournament while Cameron advanced to the second round.
In the second main round, Cameron's battle was briefly shown and Cameron's Ferrothorn was shown defeating a Morobareru.
In the third round he was matched up against Kenton where he defeated him and Kenton was eliminated from the tournament.