Harrison fought against Ash Ketchum and defeated him, although later he was defeated. Later in that episode 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 a hospital.
Harrison's Blaziken is a powerful Pokémon which defeated Ash's Charizard. After the battle with Ash, Harrison decided to not use Blaziken in the next round because he thought it was badly injured.