Ash and his friends run into a Pokémon Center to watch a big battle on the TV: Champion Cynthia defeating Elite Four Aaron! Paul is at the Pokémon Center too, and all he wants to know is whether Ash is using Chimchar's Blaze ability. While Ash has his Pokémon train against each other to prepare for the Hearthome Gym Battle, Paul quietly watches from the sidelines. Brock notices Paul and tries to talk about Paul's brother Reggie, but Paul doesn't want to hear about Reggie; he's angry that Reggie stopped battling after losing his final Battle Frontier challenge.
During a break in Ash's training, Paul comes over and gets on Ash's nerves again. Even worse, Paul taunts Ash with the badge he already won at the Hearthome Gym! As usual, the two Trainers get into an argument, and Ash wants another battle. It'll be a one-on-one, Turtwig against Paul's Honchkrow, with Paul's other Pokémon watching the match. Turtwig's speed helps it dodge Honchkrow's attacks, but Turtwig is still taking a lot of hits. Just when things are looking grim, Turtwig evolves into Grotle. However, Grotle is much bigger, and it can no longer dodge as quickly as Turtwig—so it's an easy win for Honchkrow. Strangely, even after the battle, Paul's Torterra seems preoccupied by Grotle's defeat.
That night, Grotle sneaks out of the Center to train alone. It wants to get its old speed back, but its body just can't run as quickly as it did before. Ash's Pokémon come out to watch, and Paul's Torterra emerges from the bushes as well. With Gliscor's help, Torterra demonstrates how to endure attacks without dodging, then strike at just the right moment. Grotle understands that Torterra is telling it to develop a different fighting style that suits its new form. The next morning, Ash tries to thank Paul for Torterra's help, but Paul brushes him off—what Torterra does is its own business! Paul may never change, but Ash is ready to switch things up and win his next Gym battle. Now it's back to Hearthome for him and his friends!
The episode opens showing a battle between Cynthia and Sinnoh Elite Four member Aaron competing for the championship crown. Cynthia's Garchomp and Aaron's Drapion face off. The duel is being televised, and a group of Trainers watch at a Pokémon Center, one of the observers being Paul. Ash and his friends arrive to watch the duel as well, and Ash notices Paul. On the television, Aaron orders Drapion to use Pin Missile. The duel continues until it comes down to Cynthia’s Gastrodon and Aaron’s reacquired Beautifly. Beautifly is exhausted, but it has enough to attack with SolarBeam. Gastrodon uses Stone Edge to negate the attack and knock out Beautifly at the same time. Cynthia successfully defends her title. Aaron praises his Beautifly and recalls it.
At the Center, Team Rocket snubs Aaron for losing to Cynthia while Ash and his friends muse at how Cynthia hung on to her title despite Aaron’s enthusiasm and getting his Beautifly back. Paul walks up to Ash and asks about Chimchar's Blaze, remembering how the Ability made Chimchar fly into a rage before. Ash pushes it off saying that he doesn’t need to rely on it, and Paul leaves without a word. Ash decides to train with his Pokémon in order to prepare for the Hearthome Gym. Dawn has her Pokémon team up with Turtwig, Staravia and Gliscor. They send attacks at Pikachu, Buizel and Chimchar, while those three defend with their moves. Nearby, Paul tries to read, but notices Ash’s training. A disguised Team Rocket grooms Paul's Torterra. Ash and Dawn's Pokémon continue to practice as Paul takes a closer look. Ash’s three Pokémon fly back and crash into Ash, knocking him down. Brock praises Ash’s offensive-defensive tactics, but he still needs to hold back moves from connecting.
Brock notices Paul watching and chats with him while his Happiny greets Paul's Pokémon. Brock somewhat praises Paul’s training and how he is curious about Ash’s training with Chimchar, which Paul reveals his disappointment that Ash won’t use Blaze. Brock responds by mentioning Ash's battle style and mentioning their encounter with Paul’s brother Reggie and noticing how many Badges and Symbols he obtained but had spotted that he was missing the Brave Symbol. Paul explains how Reggie had powered his way through the Battle Frontier, however a single loss at the Battle Pyramid made him decide to give up being a trainer altogether. Paul clearly detests Reggie’s lack of bitterness and states that he wants to be a better Trainer than his brother.
While Ash and his Pokémon take a moment to regroup from training, Paul and Brock approach. Chimchar is scared at the sight of its former Trainer, but Piplup and Turtwig step up to protect their friend. Paul criticizes Ash about his training methods being similar to his own, which Ash quickly denies, remembering how Paul’s Pokémon attacked Chimchar at once as part of training. Dawn mentions that Ash is training for the Hearthome Gym. Paul snubs Ash by showing him his Relic Badge. Ash is irritated at that and how Fantina’s Pokémon used Hypnosis to stop his Pokémon from doing anything, Paul irritating him more by mentioning Chimchar’s Blaze and using brute force instead. Ash challenges Paul to a battle, which he accepts, making it a one-on-one battle. Turtwig volunteers to duel.
On the battlefield, Ash’s Turtwig stands ready as Paul summons his Honchkrow. Ash checks his Pokédex. Despite the type disadvantage, Ash is confident in Turtwig’s speed. Honchkrow prepares Sky Attack, but since it takes time to ready, Turtwig strikes first with Energy Ball, but it inflicts little damage. Honchkrow charges as Turtwig jumps and spins forward, dodging the attack. Honchkrow follows up with Night Slash, but Turtwig dodges again. However, Honchkrow comes around with a second Night Slash and manages to hit. Brock scolds Ash to cut the cavalier dodging attitude and attack. Honchkrow comes down with Aerial Ace and Ash orders Turtwig to use Bite, but Honchkrow knocks Turtwig down before it can attack. Turtwig tries to get up, but Honchkrow hits with another relentless Aerial Ace. Turtwig manages to get up and begins to glow.
Right during the heat of battle, Turtwig evolves into Grotle, revitalized with new energy. Ash checks his Pokédex and is excited at his new Pokémon. Undeterred, Paul orders Honchkrow to execute another Aerial Ace. Ash tells Grotle to dodge, but as Grotle tries to, it fails to move quickly enough and gets hit. Dawn thinks that Honchkrow is still faster, but Brock realizes what is happening. Honchkrow charges up a Sky Attack as Ash tells Grotle to attack with Bite, but Grotle stumbles. Grotle manages to get up as Honchkrow charges. Grotle tries to turn around but stumbles again, taking the Sky Attack. Ash still believes Grotle retained its speed, but Paul snubs Ash at his lack of knowledge about how much his Pokémon changed after evolving. Honchkrow fires a Dark Pulse, hitting Grotle on the head and knocking it out.
The scene jumps to after the battle, Nurse Joy treating Grotle. On the other side of the window, Dawn wonders why Grotle’s speed went down when evolution normally makes a Pokémon stronger. Brock brings up the fact that Grotle weighs ten times more than Turtwig, making it difficult to adapt to the sudden increase in weight. Outside, Paul trains with Weavile and Torterra. Torterra fires Frenzy Plant at Weavile. Weavile dodges and hits Torterra with Ice Shard. Paul scolds Torterra's slow reaction as Torterra increases the attack intensity, managing to hit Weavile. Paul notices Torterra’s attention drift to the Pokémon Center and Ash’s Grotle, telling his Pokémon to let it go. After Grotle recovers, Ash and his friends gather in a room. Ash tries to cheer up his Grotle, praising the increased defense and wanting to improve its speed to balance, but Grotle still feels depressed.
During the night, Grotle is unable to sleep and tries to leave the room, but the Pokémon wake up and notice. Grotle still walks out and Pikachu gets everyone but Staravia and Piplup to follow. Outside, Grotle tries to train, running forward, but it stumbles and crashes into a rock. Grotle gets up and keeps trying to build up speed, but it keeps tripping, the Pokémon quickly losing hope. Team Rocket watches and Meowth reveals its intentions. The Pokémon meet up with Grotle, trying to reassure it, when Paul’s Torterra approaches. Pikachu prepares for a confrontation. Meanwhile, Staravia pecks at Ash, waking him up. Piplup does the same to Dawn while Croagunk uses Poison Jab to rouse Brock. Ash notices the Pokémon missing.
Outside, Torterra meets up with the Pokémon as Chimchar tries to prevent any fighting, but Torterra displays no hostility. Torterra convinces Gliscor to help demonstrate as Ash and his friends arrive, noticing Torterra but staying out of sight. Gliscor attacks Torterra with Steel Wing, but Torterra takes the hit. Gliscor hits with multiple X-Scissor attacks, but Torterra continues to stand strong as Ash, his friends, and even Team Rocket watch with awe. Dawn thinks that Torterra is unable to dodge, but Brock notices that Torterra is deliberately staying put. Gliscor attempts another X-Scissor, when Torterra stands on its hind legs and comes down, pinning Gliscor to the ground before using Frenzy Plant. Before the tree trunks hit Gliscor, Torterra stops the attack and the tree trunks withdraw. Ash realizes that Torterra just demonstrated to Grotle that defense could easily compensate for speed, and rushes out to thank Torterra. Torterra acknowledges the Trainer and praises Grotle before walking away. Ash pledges to help Grotle improve on its unique battle style and synchronizing with his Pokémon, Grotle now cheerful. Team Rocket also takes the lesson to heart and sets off in their balloon.
Torterra returns to camp as Paul approaches his Pokémon, curious about its action but not pushing the point. The next morning, Ash and his friends run into Paul and Ash thanks Paul for what his Pokémon did, but Paul brushes it off claiming non-involvement. As Paul walks away, Ash looks forward to working with his Pokémon and the upcoming Hearthome Gym battle. Ash also promises Chimchar and Grotle that in his next battle with Paul, he will win.