Like Brawly and Machop, Makuhita also enjoyed surfing the waves and used the surfing techniques it learned from Brawly in its battles. Seeing Team Rocket captured Ash's Pikachu, Brawly sent Makuhita, who attacked their boat, allowing Pikachu to blast them off. After Brawly's Machop was defeated, Brawly sent Makuhita against Ash's Treecko in a Gym battle. Like Machop, Makuhita deflected Treecko's Pound and Quick Attack. Makuhita used Vital Throw to attack Treecko and damaged it badly with Arm Thrust. Treecko attempted to attack, but was thrown by Seicmic Toss. However, when Treecko kept coming back for more, Makuhita evolved into Hariyama.
With the massive power boost it gained by evolving, Hariyama blocked Treecko's attack and defeated it easily with Knock Off, thus defeating Ash. However, due to its greater size and weight, Hariyama found surfing more difficult.
As the group were going to a cave to shelter themselves against a storm, a landslide occurred. Brawly sent his Hariyama to crush the rocks with Arm Thrust. Later on, Team Rocket attempted to steal Pikachu, but Hariyama use Arm Thrust to blast them off. During the Gym Battle, after Brawly's Machop had been defeated, Brawly sent Hariyama, who used Arm Thrust on Ash's Corphish, who protected itself with Harden. Since Hariyama was not slowing down, Corphish went into the water, then waited for the moment to use Crabhammer and dive back in. Hariyama, however, used Arm Thrust on the water, forcing Corphish to come out, who was defeated by Seismic Toss. Without further ado, Ash sent Treecko. Hariyama proceeded to attack with Arm Thrust, but Treecko evaded the attacks and pounded Hariyama on its legs, weakening it, causing it unable to use Vital Throw. During the last moments, when Hariyama and Treecko were exhausted, both Pokémon used the power of the geysers to exchange blows. In the end, Treecko managed to use Pound on Haryiama, negating its Knock Off attack and defeating it, thus making Ash the winner of the Gym match.
Before arriving to Slateport City for May's Grand Festival, she and Ash remembered their past adventures so far. Ash recalled facing Brawly and his Makuhita, who were interested in surfing. During the battle, Makuhita, who absorbed and evaded Ash's Treecko's Pound attack, evolved into a Hariyama and defeated Treecko with Knock Off. In the rematch, Treecko used Pound on Hariyama's legs, making it unable to use Vital Throw. In a final clash with the geysers, Treecko won, earning Ash the Knuckle Badge.