Lunatone first appeared in a battle with Tate's Solrock. After clashing with each other by using Tackle, Solrock used Sandstorm, but Liza's Lunatone was a Rock-type Pokémon as well, so the attack had no effect. Thus, Lunatone used Psychic and pushed Solrock onto a wall. Just as Solrock was charging for an attack, Lunatone tackled it. Just as Solrock's Solar Beam was launched, Lunatone countered it with a devastating Ice Beam, freezing and defeating Solrock at the same time. After Max and Tate landed the space shuttle, May and Liza faced Team Rocket, who tried to steal the space shuttle. May's Combusken used Fire Spin and Liza's Lunatone fired Ice Beam, which blasted Team Rocket away.
During their first Gym Battle with Ash, Tate and Liza sent Solrock and Lunatone to battle. Pikachu and Swellow attempted to attack, but Solrock and Lunatone evaded, causing Pikachu and Swellow to bash into the planet models. Afterwards, Solrock and Swellow tackled them both. Solrock launched Solar Beam and Lunatone with Ice Beam, but the moves accidentally collided. This caused Tate and Liza to argue, while Swellow used Aerial Ace on Lunatone and Pikachu using Iron Tail on Solrock. Both Solrock and Lunatone tried to Tackle Pikachu, but Swellow rescued Pikachu, causing Solrock and Lunatone to attack each other. Just as Ash wanted to finish the battle, Team Rocket appeared in the Gym, crashing it with their robot and taking Solrock and Lunatone away. Although Solrock and Lunatone tried to free themselves, the psychic powers reflected onto each other, due to the robot's properties. Fortunately, Swellow and Pikachu tracked Team Rocket in their balloon, from where Pikachu used Thunderbolt. This freed Solrock and Lunatone, who turned the tables on the villains and Team Rocket were soon the victims of their Psychic attacks. During the rematch, Pikachu tried to use Thunderbolt on Solrock, but the attack was sent back to him, due to Lunatone's Light Screen. Swellow tried using Aerial Ace, but was pushed away by Solrock's Sandstorm. Pikachu went on Swellow's back and tried using Thunderbolt once more, but Light Screen reflected the attack. Ash had Swellow use Double Team, which surrounded Solrock and Lunatone with the illusions. Lunatone and Solrock used Ice Beam and Solar Beam, which blew away the illusions. Swellow and Pikachu descended down, as they tried to make a sneak attack, but were also hit by Solar Beam and Ice Beam. Instead, Ash ordered Pikachu to aim its Thunder attack straight into the clouds. The thunder then hit Pikachu and its Flying type partner Swellow, injuring them both, but through sheer willpower, the two Pokémon absorbed the electricity and stored it in their bodies, creating a unique "Thunder Armor". Using this armor, Pikachu and Swellow overwhelmed Solrock and Lunatone, ignoring their Solar Beam and Light Screen moves and knocking them both out at the same time with Iron Tail and Aerial Ace.
Before arriving to Slateport City for May's Grand Festival, she and Ash remembered their past adventures so far. Ash recalled facing Tate and Liza in the Double Battle. Due to Pikachu and Swellow's Thunder Armor, Lunatone's attacks were negated and Lunatone was defeated.