As a Chimchar under Paul's command
Infernape was once a Chimchar owned by Paul. Prior to events of the Diamond and Pearl series, Paul saw Chimchar being chased by a group of wild Zangoose. The situation looked bad for Chimchar, but in its stress it pulled off an extremely powerful Flame Wheel. This impressed Paul enough to add Chimchar to his regular team. However, this first impression did not match up to Chimchar's normal abilities, resulting in Paul criticizing it for being weak. Since then Paul has been pushing Chimchar to the limit to duplicate the amazing power he saw before. Traumatized, Chimchar gained a morbid fear of all Zangoose.
Chimchar's first episode was When Pokémon Worlds Collide! where Paul used it to battle Ash's Aipom. It fought well, but lost in the end. Chimchar reappeared in Different Strokes for Different Blokes where it won against Ash's Turtwig.
In Shapes of Things to Come!, Paul used Chimchar in his Gym battle against Roark and his Onix. Chimchar immediately took damage from Onix's previously placed Stealth Rock, but remained standing. Chimchar than continued to use Dig until Onix was knocked out, having support from Paul's Elekid's Static Ability slowing Onix down. Chimchar then went up against Roark's Cranidos. Paul uses the same strategy again, having Chimchar dodge and attack with Dig. However, Roark has figured it out by now and deals major damage from continuous attacks from Headbutt and Zen Headbutt, causing Chimchar to activate Blaze. Chimchar attacks with a powered up Flame Wheel and followed up with Dig, but is knocked out with Headbutt, causing Paul to get angry with Chimchar for its defeat and promising to deal with it later.
After losing to Cynthia's Garchomp in Top-Down Training, Paul realized that Chimchar was not fulfilling his expectations. This culminated in the Hearthome City Tag Battle Competition, where he was forced to battle alongside Ash. That night, Ash discovered Paul's training regime, which involved his Pokémon attacking Chimchar in the hopes of recreating the power he had seen before. Ash intervened and took Chimchar to the Pokémon Center where Nurse Joy told Paul it would be unable to battle. Paul ignored this warning.
During the next battle against a Zangoose and a Metagross, Chimchar was too scared to make any attack when caught in Zangoose's claws, and had to be saved by Turtwig, who was seriously injured as a result. Chimchar made up for this by protecting Turtwig from a Fire Blast attack. Realizing that not even reliving the traumatic event of being attacked by Zangoose could motivate Chimchar to do Blaze, Paul gave up on Chimchar. For the remainder of the battle Paul refused to give Chimchar any orders. Consequently, Ash gave Chimchar commands for the remainder of the battle. After the battle, Paul released Chimchar in front of Ash. As the little Pokémon headed back to the wild, Ash invited it to join him, to which it accepted. Paul rudely commented that the two were perfect for each other: both were worthless scum.
Ash inviting Chimchar to join his party
Immediately after being released and offered to join Ash, Chimchar was kidnapped by Team Rocket, but used Flamethrower on the mecha they had used to steal it, blasting them off. It then promptly joined Ash.
In the final round of the competition, Paul and Ash selected Elekid and Chimchar for their last battle in Smells Like Team Spirit! against Conway's Heracross and Dawn's Buizel. During the battle, Elekid evolved into Electabuzz, and they both combined Thunder and Flamethrower on Buizel and Heracross to knock them out. This victory meant that Ash and Paul won the Hearthome City Tag Battle Tournament.
In Tears For Fears!, Ash and his friends had a picnic party. Chimchar watched as Ash, Dawn, and Brock's other Pokémon had fun playing, battling, and helping cook together. Chimchar began to have flashbacks of when it was still in Paul's possession, reflecting on how its former Trainer abused it and treated it like nothing more than a tool for battle, giving it a few minutes to eat before going back to extensive training, as opposed to how Ash and his friends treat their Pokémon like friends, caring for them and not pushing them too hard. Chimchar began to cry out of joy that it was finally treated with patience and kindness, something Paul failed to do as its Trainer. In the same episode, Chimchar was faced with the challenge of battling three Zangoose in order to save Ash's Pokémon. Though Chimchar had a morbid fear of Zangoose, with Ash's encouragement Chimchar was able to overcome this fear and save the other Pokémon, getting rid of Team Rocket in the process as they were sneaking off.
In A Triple Fighting Chance! Ash used Chimchar in his Gym Battle against the Veilstone City Gym Leader, Maylene. Chimchar battled Meditite, but was recalled after Meditite confused it. It was then sent out against Lucario where it was ultimately defeated, despite a valiant effort.
In Chim - Charred! Ash, Dawn, and Brock ran into Paul. Ash and Paul had an argument about training methods, and an enraged Ash challenged Paul to a battle. Chimchar volunteered to go up against Paul and faced Paul's Ursaring. Ursaring and Paul used brutal tactics, and Chimchar was pushed to the point of using Blaze. Chimchar easily defeated Ursaring, but went on an uncontrollable rampage. Ash grabbed a flaming Chimchar, begging it to stop. Chimchar continued to struggle and even went as far as to bite Ash in its rage. Eventually, after being embraced by Ash, Chimchar calmed down.
Later in Double Team Turnover!, when battling Team Galactic, Chimchar protected Pikachu from a Poison Jab launched by Saturn's Toxicroak. Chimchar was incapacitated for the rest of the fight, and was later thanked by Ash (after receiving medical treatment). Cynthia then comforted Chimchar about its past with Paul.
Ash later used Chimchar to battle against Barry in Barry's Busting Out All Over!. Chimchar easily defeated Barry's Staraptor, using its superior agility. However, despite the type advantage, Chimchar lost to Barry's Roserade.
In Shield with a Twist!, Ash used Chimchar as his second Pokémon in his Hearthome City Gym Battle, it went up against Fantina's Mismagius, Fantina mentioned earlier that Mismagius couldn't use Hypnosis, which was her main strategy in their last battle. Chimchar used Flame Wheel, which was dodged and then Mismagius used Psywave hitting Chimchar, Chimchar then spun and used Flamethrower, creating a Fire Counter Shield, which hit Mismagius, and Mismagius was unable to escape with Psywave, but Counter Shield was broken by Mismagius' Magical Leaf. Chimchar then used Flame Wheel, while Mismagius used Dark Pulse, Chimchar then used Flamethrower, adding Counter Shield blocking Dark Pulse. Mismagius then used Psywave, but this only blocked the Flamethrower allowing Chimchar to hit with Flame Wheel knocking Mismagius out. Chimchar was then recalled. Chimchar was later sent out as Ash's last Pokémon to battle against Fantina's Drifblim, its Flame Wheel was countered by Will-O-Wisp, but this gave Ash an idea, Chimchar then used Flamethrower, but was countered by Drifblim's Will-O-Wisp and Psychic Counter Shield. However, this only powered up Flamethrower, thus making it deal massive damage, Ominous Wind was dodged by Dig; Chimchar then came from behind and grabbed onto Drifblim, crashing it into the ground, Drifblim then used Hypnosis, but Chimchar used Flamethrower, knocking out Drifblim and earning Ash the Relic Badge.
In Dealing With Defensive Types!, it was Ash's first Pokémon in his battle against Byron, it took on Byron's Bronzor, Roark quickly identified it as Paul's Chimchar, first Chimchar used its Flamethrower but didn't do much damage due to its ability Heatproof, Chimchar tried using Flamethrower again, but it was countered by Rain Dance and dealt damage to Chimchar. Chimchar escaped by using Dig but its Flamethrower was countered by Gyro Ball, then Chimchar's Flame Wheel clashed with Gyro Ball, knocking Bronzor out. After Buizel was defeated, it was sent out again against Byron's Steelix, after using a Flamethrower, Chimchar was shown to be weak from the last battle, it then used Dig to dodge Iron Tail but Steelix used Iron Tail to shake the ground and emerge Chimchar and deal damage, this happened again when Chimchar dodged Bind, then just as Chimchar was about to be caught by a second Bind, the ground collapsed on Steelix due to it being weakened by Dig, allowing Chimchar to finish it off with Flame Wheel. It then went up against Bastiodon, its Flamethrower got countered with Iron Defense and then Metal Burst, which returned the damage, knocking Chimchar out.
In Sliding Into Seventh!, it was Ash's fourth Pokémon in his Snowpoint Gym Battle. Chimchar battled Candice's Snover, after dodging Ice Beam, its Flamethrower clashed with her Icy Wind creating water vapour, Ash told Chimchar not to panic and to sense Snover's movements, when it sensed her, it used Flamethrower, knocking her out. It then went up against Candice's Abomasnow, its Flamethrower was overpowered by her Blizzard, knocking it backward. Ash then recalled Chimchar. It was later sent out again against Abomasnow once again after Staraptor and Grotle were defeated. Its Flamethrower was overpowered by Blizzard again but Chimchar was able to dodge. It struggled to dodge its next two attacks. Ash then decided to rely on speed after power wasn't enough, but didn't know how. After Chimchar dodged Blizzard, Ice Shard and Wood Hammer, Ash saw ice break, and told Chimchar to jump on an ice pillar. After Abomasnow broke the ice, Chimchar jumped on a piece of ice and used it like a snowboard, increasing its speed and launched multiple successful Flamethrowers. After dodging more attacks, Abomasnow become tired. Flame Wheel went up against Blizzard, creating more water vapor, but Abomasnow was already knocked out. This won Ash the Icicle Badge.
In Evolving Strategies!, Chimchar was used in the full battle Ash had against Paul. It defeated Paul's Ursaring, which had previously taken down three of Ash's Pokémon, and evolved soon after into a Monferno, immediately learning Mach Punch. During the following battle against Paul's Electabuzz, it put up a very close fight, but was defeated in a clash of Mach Punch and Thunder Punch, and badly injured, resulting in a loss for Ash.
In Uncrushing Defeat!, Monferno, along with the rest of Ash's Pokémon, was badly injured. It needed a Cheri Berry to help treat it, but the Pokémon Center didn't have one. After Brock got one by Lake Acuity, it became recovered slightly. It eventually attacked Team Rocket in combination with Ash's other Pokémon.
In Bagged Then Tagged!, it was used in a Tag Battle with Dawn against Lyra and Khoury. Monferno used Flamethrower on Dawn's Cyndaquil's Flame Wheel to defeat Lyra's Chikorita, and defeated Khoury's newly evolved Croconaw with a Mach Punch.
Infernape's Ability activated
In Fighting Ire with Fire!, Monferno battled Barry's Empoleon. After being struck by a Hydro Cannon and sent crashing into the forest nearby, Monferno entered once again into an uncontrollable rampage with Blaze, but managed to control it in the last second in order to save Ash's Pikachu, Dawn's Piplup, Paul's Electabuzz and Barry's Empoleon from Team Rocket's falling mecha, evolving into an Infernape in the process.
In Flint Sparks the Fire!, Ash used Infernape in a battle against Flint's Infernape. However, despite its power and speed, it was unable to keep up with Flint's Infernape and was quickly knocked out with a Mach Punch.
In The Eighth Wonder of the Sinnoh World!, Infernape was Ash's third Pokémon in Ash's rematch against Volkner. It went up against Volkner's Jolteon, Infernape launched a Mach Punch only to be hit with a powerful Thunderbolt; after dodging one Shadow Ball, it blocked the others with Mach Punch. Afterwards, Jolteon jumped in the air and went for a Shadow Ball, but Infernape used Mach Punch before Shadow Ball was launched, knocking Jolteon out. Infernape was then recalled. It was later sent out against Volkner's last Pokémon, Luxray, Infernape's Flamethrower drew with Luxray's equally powerful Shock Wave. Luxray then dodged its Mach Punch with Double Team. Though Infernape destroyed all the clones, it was hit with Thunder Fang; after dodging Shock Wave, Infernape went for Mach Punch, which was dodged and it was then hit with Thunder Fang. It dodged a second with Dig. However, Luxray used Iron Tail to hit the ground, exposing Infernape and dealing lots of damage. Luxray then went to finish off a downed Infernape with Thunder Fang, but was interrupted by Team Rocket knocking out the power. Then Infernape's Blaze activated, it initially went out of control with Flamethrower hitting the wall and roof. But when Ash told Infernape to stop, it walked over to Ash, but was able to listen to him, and it controlled Blaze for the first time. Obeying Ash, it launched an extremely powerful Flamethrower, but was hit by Thunder Fang, which Infernape easily countered with Mach Punch. It then countered Iron Tail with a fast Mach Punch. It then knocked Luxray out with Flame Wheel, winning Ash the Beacon Badge.
Before the Lily of the Valley Conference, Ash decided he would need help from his previously caught Pokémon. Due to this, Infernape, along with Ash's Sinnoh party except for Pikachu were all sent to Professor Oak's Laboratory. Later during the tournament Ash recalled Infernape to his team and trained against Brock's Sudowoodo to improve Flame Wheel when Infernape suddenly learned Flare Blitz. Ash planned to use it along with his Torterra and Glalie, but after Dawn said power may not be enough, he decided not to use sheer power and instead used different Pokémon.
The rivalry between Infernape and Electivire
Infernape was later used in the full battle against Paul's Aggron, where it managed to burn Aggron with Flare Blitz before finally defeating it with Mach Punch. Ash decided to recall it when Paul sent out his Gastrodon. Later on it was sent out again to battle Paul's Ninjask. Ninjask's Agility was getting the better of it so Ash told it to use Dig then Flare Blitz which heated up the field, causing fire to erupt out of the ground, which made a mist cover the whole field that drastically damaged Ninjask and also cancelled Drapion's Toxic Spikes attack. After putting up a good fight, Infernape was able to put an end to Ninjask's lightning speed with a Mach Punch, evening the score. Infernape's final opponent was Paul's Electivire in a heated battle in Battling a Thaw in Relations!. Infernape initially caused Electivire severe damage, but after a while, it was caught by Electivire's tail, and took so much damage from Electivire's Thunder attack that the referee had almost declared it unable to battle. But, Blaze was once again activated, giving Infernape the strength to defeat the Thunderbolt Pokémon with a devastating Flare Blitz attack, giving Ash his first victory against Paul, as well as access to the Semifinal Round of the Lily of the Valley Conference.
Ash left Infernape at Professor Oak's Laboratory when he decided to go to Unova.
Infernape was reunited with Ash in The Dream Continues!, where it and the rest of Ash's Pokémon posed in a group photo with him.