Harrison first met Ash Ketchum and his friends at the Ho-Oh shrine. Harrison also wanted to try to fix the problem that occurred at the Ho-Oh shrine. At the shrine, a Sneasel was causing trouble and Harrison decided to battle it. After winning the battle, Harrison caught Sneasel. Harrison fought against Ash in the Quarter-final round and defeated him, although later he was defeated by Jon Dickson in the semi-finals. Later on, he helped Ash, Gary Oak, Brock, Misty and some others free a group of Misdreavus from under a fallen tree. He is good friends with Gary Oak. It is also known that in his battle with Ash in the Silver Conference, he managed to put Ash's Charizard in the Pokémon Center.
- Kanto Conference (Indigo League): Unknown
- Silver Conference (Johto League): Loses to Jon Dickson - Top 4
- Ever Grande Conference (Hoenn League): Unknown