Chili received his Pansear at a young age when his brothers were also given their first Pokémon. It debuted in Triple Leaders, Team Threats!, where Chili introduced it to Ash, who scanned it with his Pokédex before battling.
Pansear was the first Pokémon Ash faced in his Striaton CityGymbattle, where it went up against Ash's Tepig. Because it was Tepig's first battle with Ash as his Trainer, Chili felt Pansear had the advantage. Pansear managed to put up a good fight against Tepig with its powerful Dig attack, along with Fire Punch that sent Tepig flying. However, Tepig dove into the tunnels after Pansear and bit down on its tail which caused Pansear extreme pain. Tepig then spun Pansear around by its tail and threw it across the field, then followed up with Ember and Tackled it into the wall, knocking Pansear out.
Pansear returned in A Call for Brotherly Love!, when Chili arrived at Driftveil City to battle Cilan, where Pansear happily greeted its friend Pansage. During the battle, it was revealed to have learned Flame Charge and Fire Blast. Despite having a type advantage, it lost against Pansage. Pansage helped it to its feet, and when Chili tried to recall Pansear, Pansear avoided the Poké Ball's light and Chili scolded it for losing. Angered, Pansear scorched Chili and ran away. After Cilan spoke to Cress, and learned of Chili's situation, the brothers found Pansear eating apples in a tree. When Chili asked Pansear to come down and talk, Pansear threw an apple at him, so Pansage climbed up the tree and tried reasoning with it instead. Chili then climbed up the tree, apologized to Pansear for getting angry, and told it that he wanted to help it train. Pansear accepted his Trainer's apology, and the pair began taking advice from Cilan.
Cilan proposed that Pansear learn a new move to help defend it against Water-type Pokémon, since all of its moves at the time were Fire-type moves. The team decided to help Pansear learn Solar Beam, and they all started to train with it. First, they worked to absorb the sun's energy, then Pansage taught it how to harness the energy and fire it in a beam of light. Pansear tried but failed to successfully use Solar Beam, so they generally worked on training its strength, putting it through various exercises. At the end of the training session, it was successfully able to perform Solar Beam. Overjoyed, Ash challenged Chili to a match to see how much stronger Pansear had gotten. Pansear then battled against Ash's Oshawott and successfully managed to defeat it. Happily, Pansear leapt into Chili's arms and the two embraced in a hug. The pair then thanked Cilan and Pansage for all their help, and bid them farewell.
Pansear is generally friendly and loves to battle. It is very determined to do its best in any circumstance. However, it shares a temper with its Trainer, Chili, as well as a love for food when upset, something that has been pointed out by Cilan. These similarities often cause the two to butt heads, but they do genuinely care for one another, and the similarities will bring them back together.
Simisear first appeared as a Pansear. It assists Chili and his brothers in the kitchen by using its flames to heat up tea for their customers. Simisear, as a Pansear, first appeared in Welcome to Striaton City!!, with its Trainer at the Striaton Gym where it uses the flames on its head to prepare tea for Black, Cheren and Bianca.
Later, it is used in the Gym Battle against Black, Cheren and Bianca alongside Chili's brothers' Pokémon. They proved powerful against Black's Tep, Bianca's Oshawott and Cheren's Snivy with their type advantages. Eventually, Pansear ended up being knocked out by Bianca's Oshawott after being hit by its water-soaked scalchop.
In The Shadow Triad, Pansear was used to battle the Shadow Triad at the P2 Lab. Although it, Pansage, and Panpour were at a disadvantage against their opponents, their Trainers gave them a boost of power by evolving them with their respective evolutionary stone. Pansear evolves into a Simisear, but is still unable to defeat its opponent despite becoming stronger. Eventually, they are saved by Cobalion, Terrakion, and Virizion, who attacked both groups to rescue the Keldeo the Shadow Triad had captured.
A † shows that the move was used recently, unless all moves fit this case or there are fewer than five known moves.
In the Pocket Monsters BW manga
In the Pocket Monsters BW manga, Chili appears with a Pansear who participates in a battle with Clefairy. Pansear teams with the brothers' Elemental monkeys. During the battle, Clefairy uses the attacks shot from the monkeys including Pansear's unidentified Fire-type move to his advantage for making green tea.