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 the Pokémon Center.
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.