Heliolisk debuted in Clemont's Got a Secret!. When Clemont had a battle with Clembot to determine official ownership of the Gym, Clembot sent out Heliolisk against Clemont's Bunnelby. During Clemont's time away from the Gym, Heliolisk was taught how to counter opponents using Dig, which was seen when Heliolisk used Bulldoze on Bunnelby. Bunnelby turned the tables by confusing Clembot and Heliolisk was subdued by Bunnelby's combo of Dig and Mud Shot. After the battle, Clemont ran to it to see if it was okay in which Heliolisk responded that it was. Heliolisk then cheered along with the group after Clemont was able to reprogram Clembot.
In The Moment of Lumiose Truth!, Heliolisk was used in a Gym battle and his second choice against Ash. It first went up against Ash's Goodra. Heliolisk was quicker than Goodra as none of Goodra's attacks were able to hit it. Ash recalled Goodra after Heliolisk paralyzed it with Thunder Wave. Heliolisk's next opponent was Ash's Hawlucha, who was picked to match Heliolisk's speed. When Heliolisk began to use Flash and opened its collar, Ash had Hawlucha use High Jump Kick on the exposed collar, knocking Heliolisk out. After Ash's victory, it was left back with Clembot at the gym along with Magnemite and Magneton.
Little is known about Heliolisk's personality due to how little screentime it has gotten from staying at the Lumiose Gym. It is Clemont and Clembot's main battling Pokémon, preferring it over Magnemite and Magneton. It is a skilled and speedy battler, easily running circles around its opponents and using Parabolic Charge to recover its health. In The Moment of Lumiose Truth!, it was revealed its collar is a weak point for Heliolisk, who extends it when attacking.
Heliolisk is a very happy and energetic Pokémon, dancing on the battlefield when it saw Clemont was there. It takes Clemont's orders seriously, giving its all in battle against its Trainer and Bunnelby. Heliolisk works well with both its Trainer and his invention Clembot.