The good news for Ash and his friends is that they've entered a tag battle tournament in Hearthome City and everyone made it past the first round. The bad news? Paul is Ash's partner and the two of them just can't get along. Before the second round, Paul has his Pokémon team up against Chimchar to deliver some harsh training. Even Team Rocket thinks Paul is being cruel to Chimchar! It's all too much for Ash, who insists on taking Chimchar to the Pokémon Center.
At the Pokémon Center, Brock asks Paul to explain himself. Paul describes how he first met Chimchar: it was cornered by a group of relentless Zangoose and looked to be in serious trouble. Pushed to its limit, Chimchar let loose with a mighty Flame Wheel that knocked out all its foes! Paul immediately asked Chimchar to join him, but since that day, Chimchar hasn't been able to recapture that same power. And now, Nurse Joy and Brock tell Paul he has to give Chimchar a rest.
But at the tournament the next day, Paul sends Chimchar in to battle alongside Ash's Turtwig. What's worse, their tag battle opponents are fielding a Metagross and a Zangoose! Once again, Ash and Paul simply can't cooperate. Paul doesn't even care when Chimchar's Flame Wheel hurts Turtwig! But when Chimchar freezes in fear at painful memories of its battle with the group of Zangoose, Turtwig still comes to the rescue.
Disgusted, Paul turns his back on Chimchar, and Ash gives Chimchar and Turtwig commands so they can win the battle. After the match, Paul releases Chimchar—for good. As Paul walks away, Ash asks the unhappy Chimchar if it wants to come with him instead...
The Hearthome City Tag Battle Competition continues as the teams of Ash and Paul, Dawn and Conway, and Brock and Holly advance to the second round. During the night, Ash trains with his Pokémon, having Staravia use Aerial Ace. Aipom, Turtwig, and Pikachu dodge the attack with the spinning maneuver Dawn taught them before. Staravia then notices a blast of energy nearby. Meanwhile, Brock offers his help to Nurse Joy at the Pokémon Center, who is overwhelmed with all of the Trainers who need their Pokémon healed. After talking with Conway for a bit, Dawn and Piplup run off to find Ash.
Elsewhere, Paul's Chimchar takes several attacks from Paul's other Pokémon. Elekid uses Thunder, Murkrow uses Shadow Ball, Torterra uses Hyper Beam, and Ursaring uses Focus Blast. The tidal wave of attacks converges as Chimchar uses Flame Wheel to defend himself. Ash notices the brutal training as Chimchar unleashes Flamethrower, hits him and makes him fall down. Team Rocket watches nearby as Ash gets up, complimenting Chimchar's power. Paul calls Chimchar back for more training as Ash questions Paul's aggressive tactics, just before Dawn arrives. Paul brushes him off as he reveals his intention to get his Pokémon exposed to powerful battles. Dawn scolds Paul for his selfish goals, but he brushes her off as well, mentioning that he needed Chimchar to be struck by the super-effective Surf attack from his and Ash's previous battle, the reason being because he feels that improving a Pokémon's weak points makes it grow stronger (which explains why he looked irritated after Ash prevented this from happening). Ash tells him that he should instead be trying to raise Chimchar's strong points, but Paul replies that that is a waste of time, and, to Dawn and Ash's surprise, that this is exactly what Chimchar wants. Ash, believing this is the hard way, tries to convince Chimchar that there are better ways to improve, but Paul and his team walk away, so Chimchar must follow. After hearing this exchange, Team Rocket wants to take Chimchar for themselves to get the Soothe Bell.
Paul continues training Chimchar as he dodges Ursaring's Hammer Arm. Torterra then fires Leaf Storm and Chimchar gets caught in it, after which Murkrow executes a Sky Attack. Paul tells Chimchar to counter with Flamethrower, but he cannot bring himself to do so and falls down after taking the hit from Sky Attack. Paul orders Chimchar to stand up, and he tries to, but is too weak from all the damage he's taken and collapses. Paul orders Elekid to wake Chimchar up with Thunder, but Ash's Pikachu rushes in with Volt Tackle to protect him. Elekid charges for another attack, but Ash and Dawn rush in and stop the fight, before taking Chimchar to the Pokémon Center. At the Center, Brock treats Chimchar, and his talent impresses Holly. Brock steps out and mentions that Chimchar needs rest, before confronting Paul about his harsh and unusual training methods. Although Paul is reluctant to reply at first, he starts talking after Brock explains that he is asking for Chimchar's sake rather than Ash's.
In a flashback, Paul tells the story of how he met Chimchar; right after capturing a Ninjask, he noticed a Chimchar racing through the forest, with several Zangoose in hot pursuit, relentlessly attacking him at every turn for unknown reasons. Paul then decided to follow them, and Chimchar eventually wound up cornered at the edge of a cliff, as the Zangoose lunged torward him. However, Chimchar activated his Blaze Ability and used a powerful Flame Wheel to consume the area with a spiral of fire, chasing the Zangoose away. After witnessing such mind-blowing power, Paul decided to catch Chimchar, wanting to utilize said power to win the Sinnoh League. This makes Brock and everyone else finally understand why Paul has always been harder on Chimchar than his other Pokémon; to recreate the stress of when the Zangoose were attacking him to push him to be able to activate Blaze at will, though he has never had any success. Paul believes he must push Chimchar way beyond the limit, but, in vain, Ash and his friends try to convince him to let Chimchar get the rest he so desperately needs. It is only after Nurse Joy's insistence that he seemingly complies.
The next day, the tournament continues as Dawn and Conway and Brock and Holly win their battles and make it to the next round. Ash and Paul fight in the last battle of the day, and Ash chooses Turtwig. Paul shocks everyone by calling out Chimchar, revealing that he only pretended to agree to let him rest to get everyone off his back. Since Chimchar still hasn't fully recovered, Ash informs Turtwig to protect him during the battle. Their opponents send out a Metagross and, to Paul's elation, a Zangoose, which puts Chimchar into a state of fear. The battle starts as Metagross charges in with Bullet Punch. Paul commands Chimchar to use Flamethrower, but Zangoose jumps in, rendering him too scared to make any moves. Turtwig uses Razor Leaf, but Zangoose swats the attack away. Metagross lands Bullet Punch on Chimchar as Zangoose hits Turtwig with a super-effective X-Scissor. Chimchar then goes in for a Dig on Metagross, but it uses Magnet Rise to dodge, before Zangoose jumps in with a Crush Claw that hits Chimchar hard. Turtwig then attempts to Tackle Zangoose, but it dodges and Metagross uses Psychic to send Turtwig crashing into Chimchar. Zangoose then rushes in with another Crush Claw in tow, and Chimchar, paralyzed by fear, cannot move a muscle. However, Turtwig saves him by using Bite on Zangoose's claws to stop the attack.
Metagross charges in with Bullet Punch, and Paul, sick of Ash getting in his way of unleashing Chimchar's Blaze, orders Chimchar to use Flame Wheel... on Turtwig! Chimchar refuses to attack his teammate, but Paul forces him to comply. Chimchar does so and hits Turtwig and Zangoose, separating them, and is able to keep the momentum going and hits Metagross as well. Turtwig suffers major damage as a result of this, and Ash is furious with Paul for intentionally harming his Pokémon. Zangoose uses another Crush Claw and Paul commands Chimchar to use Flame Wheel again, but Zangoose pins him to the ground before he can do so. Paul then orders Chimchar to use Flamethrower, but looking Zangoose in the eyes has him too scared to make any moves. Turtwig uses Razor Leaf to get Zangoose off of Chimchar, before collapsing from all the damage he's taken. Zangoose then unleashes a Fire Blast towards the incapacitated Turtwig, but Chimchar repays his debt to Turtwig and blocks the attack (safe from Paul's command), powering up in the process. As Metagross heads in with another Bullet Punch, Ash and Chimchar await Paul's command, but now that it is apparent to him that not even reliving the exact catalyst that enabled Chimchar to activate Blaze in the first place is working, Paul completely gives up on Chimchar and turns away. Ash, not wanting to give up, orders Chimchar to use Flamethrower, stunning everyone. Chimchar does so and hits Metagross, knocking it out. Turtwig takes it from here and, after spin dodging a Crush Claw, uses Razor Leaf and Tackle to finish Zangoose off, giving Ash and Paul the win and entry into the semifinals. As Ash praises the two Pokémon for winning, Paul still has his back turned, and Chimchar's worried expression shows that he knows what is in store for him.
At sunset, Paul releases Chimchar, tells him to get lost, and turns to leave. Ash and his friends arrive and scold Paul for throwing all of his hard work and training away, but Paul could not care less and walks off. As Chimchar also turns to leave, Ash is upset to see such a loyal and hardworking Pokémon treated like this. Inspiration suddenly strikes him and he decides to offer the Chimp Pokémon a spot on his team, stunning Dawn, Brock, and even Paul, now stopped in his tracks. Ash steps up to Chimchar and kneels down, leaving him with an important decision to make...