Ash and Paul are still in the middle of their Full Battle, both sides down one Pokémon. Ash's Pikachu faces off against Paul's powerful Magmortar. Ash warns Pikachu not to let its guard down. Dawn, who is on the sidelines with Brock, Reggie and her Piplup (as well as Jessie, James and Meowth in disguise manning the scoreboard), looks up Magmortar in her Pokédex. Dawn wonders why Paul did not counter with a Ground-type Pokémon, but Brock suggests that it wouldn't have mattered because Ash could simply switch with Buizel at any time. Reggie adds that Paul is not only thinking about type, and as the battle continues they would find out why Magmortar's up.
Ash orders Pikachu to use Quick Attack, which successfully connects and knocks Magmortar backwards, but Magmortar quickly recovers. Even worse, once Pikachu lands, he is immediately hurt by fire that surrounds his body. Dawn wonders how Pikachu was hurt when Magmortar did not do a thing, and Brock explains that Magmortar has the Flame Body Ability, which has a chance of burning an opponent if it makes physical contact, as a result of Pikachu's Quick Attack. Paul smiles, and Ash asks Pikachu if he wants to continue, and Pikachu, desperate to help defeat Paul, agrees. Ash thanks Pikachu and commands a Thunderbolt, and Paul responds by ordering a Flamethrower. Magmortar fires Flamethrower from its massive bazooka-like arms and it connects with Thunderbolt, causing a massive explosion. Ash then has Pikachu use Volt Tackle, and Pikachu powers up and heads straight towards Magmortar. Paul commands Magmortar to use Rock Tomb, and Magmortar starts to fire purple energy which turns into rocks when they hit the ground. Pikachu, forced to run straight due to the Volt Tackle, smashes head-first into the rocks which causes Volt Tackle to fail and throws Pikachu back, where he continues to suffer from his burn. Paul then commands Magmortar to use Smog and Magmortar releasing a poisonous cloud which heads straight towards Pikachu. Ash commands Pikachu to use the Counter Shield technique which they developed for the Gym battle against Fantina, and Pikachu rolls on his back while releasing electricity, successfully countering the Smog, to which Paul is shocked and Team Rocket amazed. Reggie is impressed by the move and Brock explains that Ash developed it as a means to both attack and defend at the same time. Pikachu is then hurt by his burn again. Reggie knows that this is bad and that the longer that Pikachu carries on the greater the disadvantage for him. Paul orders Magmortar to use Flamethrower. Ash tells Pikachu to jump and use Iron Tail from above. Pikachu jumps out of the Flamethrower's path and successfully strikes Magmortar across the head with Iron Tail, but Magmortar takes the hit and Pikachu takes more burn damage. Ash then recalls Pikachu for some rest after battling so hard.
Ash decides to use type-advantage against Magmortar and sends out Buizel who is ready to battle. Ash starts by ordering an Aqua Jet and Buizel speeds towards Magmortar and hits it directly on the chest, sending Magmortar reeling back, but despite the super-effective hit is still able to carry on. Ash then follows up with Water Pulse and Buizel sends a wave of water towards his opponent, however Paul orders another Rock Tomb, and Magmortar creates a shield of rocks which protects itself from the Water Pulse. However, Ash knows that it will stand no chance against a Water-type-type attack and orders Aqua Jet. Buizel smashes through the rocks, only to find Magmortar gone. Ash and Buizel don't know where Magmortar is, and Buizel looks up to see a now aerial Magmortar release another Smog, which hits Buizel and poisons the Pokémon, causing Buizel to reel in pain. Brock realizes that Rock Tomb was used to keep Buizel from seeing what Magmortar was up to. As Buizel tries to recover from his damage, Magmortar lands and Paul recalls it.
Paul then sends out Ursaring and Ash orders Water Gun. Paul is prepared for this and orders a Hammer Arm, which successfully counters the attack making Ash wondering how it managed to counter Water Gun. Paul then orders Bulk Up which increases Ursaring's strength and defense. Ash knows what Bulk Up does, but foolishly believes Buizel can handle it and has him use Aqua Jet while Paul orders Ursaring to use Slash. Ursaring, after resisting Aqua Jet, hits Buizel with its sharp claws, sending Buizel to the ground. Ursaring uses Focus Blast, and Ash responds by having Buizel use an Aqua Jet Counter Shield which creates a typhoon of water upon which Focus Blast backfires onto Ursaring. Ash asks Paul if he likes the taste of the Counter Shield and that Pikachu isn't the only one who can use it, to which Paul says nothing. Ash then orders a SonicBoom, and Paul tells Ursaring to use Hammer Arm. Ursaring runs through the SonicBoom and lands a direct hit on Buizel, smashing him to the ground. At this point, Ash is ready to recall Buizel, but Buizel wants to stay in the battle so Ash allows him to stay. This turns out to be a mistake, because when Buizel is ordered to use Aqua Jet, the attack is countered by a dead on Focus Blast which takes Buizel out of the battle. Dawn feels very sorry for Buizel, but Reggie says that Buizel was eliminated because of Ash's poor judgment. Again, Brock agrees, saying that Ash should have recalled Buizel before the Focus Blast like he had been planning to.
Ash then sends out Staraptor, launching Aerial Ace. Paul orders another Hammer Arm, but Staraptor dodges it and scores a clean hit with Aerial Ace. Paul orders Focus Blast, which hits Staraptor in mid-air, but not critically damaging it. Ash orders Staraptor to use Close Combat, but Ursaring's Slash attack stops Staraptor before it can get close enough to attack. Ursaring then Hammer Arms Staraptor into the ground, taking it out of the match. Ash returns it to its Poké Ball and thanks it for a good battle. Paul recalls Ursaring and sends out Electabuzz, and Ash sends out Chimchar for its first appearance in the battle. Team Rocket are excited to see Chimchar battle, and Chimchar shows a mean look at Paul.
Chimchar uses Flamethrower, but Electabuzz uses Protect to block. Paul has Electabuzz put up a Light Screen before immediately returning it to its Poké Ball. While Jessie, James and Meowth complain about the constant switching of Pokémon, meaning more work for them, Brock is surprised at how Paul got Electabuzz to use Protect and then Light Screen. Reggie believes that Paul used Protect to cover Electabuzz then Light Screen to cover his next Pokémon. Paul sends out Torterra, which confuses Ash as Torterra, being a partial Grass-type, has a disadvantage to Chimchar, but he carries on.
Ash orders Chimchar to use Flame Wheel, but Torterra counters with Stone Edge. Ash has Chimchar immediately dodge the Stone Edge by changing the direction of the Flame Wheel, but it is revealed that Paul has trained Torterra to change the direction of the stones, allowing them to follow Chimchar, amazing Brock and Dawn. Chimchar cannot outrun the stones and therefore suffers a hit. Ash has Chimchar use Flamethrower which hits successfully, but the Light Screen protects Torterra and Flamethrower only does half the damage. Brock knows it is getting really hard for Ash and Reggie adds that Chimchar is in a difficult position. If it uses attacks from far away they won't cause much damage due to the Light Screen while if Chimchar goes in close it risks taking a hit from Stone Edge. Realizing that Chimchar won't be able to defeat Torterra like this, Ash recalls it, making Jessie complain loudly about the extra work that Ash was giving them by switching Pokémon. Ash sends out Gliscor against Torterra again and orders X-Scissor. However, this time, Paul isn't messing around with Gliscor and has Torterra use Frenzy Plant which this time is able to score a direct hit and knocks out Gliscor immediately. Ash returns Gliscor to its Poké Ball, and begins to consider his remaining options. He knows that Torterra was Paul's first Pokémon and as a result is the strongest member of his team. Suddenly Pikachu requests to go up against Torterra, but Ash is hesitant and reminds Pikachu of the type-disadvantage. Pikachu insists on going in and Ash agrees, planning to use speed and Iron Tail to gain the advantage, only for Paul to immediately return Torterra.
Paul sends out Ursaring again, leaving Ash unsure of what to do, as he knows that Ursaring is very powerful, having taken out two of his Pokémon. Pikachu reminds Ash that he has the first move, and Ash orders Quick Attack, while Paul orders yet another Hammer Arm. Pikachu hits with Quick Attack, but Ursaring's Hammer Arm knocks the wind out of Pikachu and sends him flying back. Pikachu recovers and Ash orders Pikachu to use Iron Tail. Paul orders Ursaring to counter, but Ursaring suffers from paralysis from Pikachu's Static, and Iron Tail scores a clean hit, although Pikachu still suffers damage from the burn it received from Magmortar earlier. Just then, Ursaring's eyes begin to glow red, pleasing Paul. Reggie notes that Ursaring's Guts Ability has been activated by its paralysis. Pikachu looks up to see Ursaring glowing red and screaming with rage, having suddenly just gained a lot of power. Paul commands Hammer Arm, while Ash orders Pikachu to counter, and Pikachu responds with a massive Thunderbolt, but it does not stop Ursaring. Ash wonders where the power is coming from, and Dawn points out that Ursaring hasn't even used Bulk up. Pikachu is Hammer Armed, and heaved into Lake Acuity, where after disappearing under the water, it lets out a final burst of electricity. Ash runs into the lake looking for his partner, while Reggie explains that Guts works by using the fact that Ursaring was suffering from a status condition to raise its attack power. Dawn and Piplup are very worried about Pikachu, and even Paul casts a glance towards the lake where Ash is looking. Pikachu emerges from the water, seemingly okay, but he quickly faints in Ash's arms, not only exhausted but injured from Ursaring's attacks. Team Rocket are shocked that not even Pikachu could manage to take down any of Paul's Pokémon. Ash carries Pikachu to the sidelines and promises to get it to a Pokémon Center after the battle. Ash knows that Paul still has five Pokémon while Ash is down to only Chimchar, but he also knows that all of Paul's Pokémon have taken damage and he is still determined to continue, which concerns Pikachu.
Ash sends out Chimchar while Paul leaves Ursaring in. Chimchar uses Flame Wheel, but Ursaring knocks it back with Slash. Ash then tells Chimchar to use Flamethrower, which scores a direct hit, and Ash then has Chimchar use Dig. Paul commands Ursaring to use Hammer Arm on the ground like before, but this time Chimchar emerges from the ground before Ursaring can pull off the attack and causes even more damage to it. Chimchar is then commanded to use another Flamethrower, which hits Ursaring dead-on finally bringing it down. Ash congratulates Chimchar on doing a great job which makes the Chimp Pokémon dance with joy. Jessie, James and Meowth cry with joy at seeing Chimchar do so well.
Ash approaches Chimchar and praises his Pokémon before asking if it is okay to continue. Chimchar nods its head in agreement and then starts to glow... as Chimchar has started to evolve! Everyone watches in amazement as Chimchar undergoes the transformation and evolves into Monferno. Ash is overjoyed over having a new Pokémon, and Dawn looks up Monferno in the Pokédex. Reggie notes that while Chimchar didn't fit Paul's training style, it was a perfect match for Ash's, and this has been displayed in Chimchar rising to Ash's call and evolving into Monferno, and as a result now has new abilities and techniques at its disposal. Monferno demonstrates this by swinging its fists quickly and effortlessly which causes them to glow. Monferno then swings at the ground which sends a gust of wind at Paul, who stands unflinching. Ash realizes that, as well as evolving, Monferno has also learned Mach Punch, which Monferno confirms by somersaulting on the spot. Reggie continues that Ash and Monferno are the perfect example of how compatibility between Trainer and Pokémon can mean everything. Also as they both have pride on the line all this will have a massive effect in the long run... this is why Reggie asked for the Full Battle; to give both Ash and Paul the chance to grow stronger as well as their Pokémon.
Paul sends out Electabuzz, who is initially surprised to see Chimchar has evolved but is still more than ready to battle its former teammate, a sentiment Monferno agrees with. Reggie notes the two are now on equal terms, and Ash commands Monferno to use Mach Punch. Monferno speeds towards Electabuzz and chokes it square on the chest, sending an astounded Electabuzz flying back and smashing into a rock. Paul orders Electabuzz to use Thunder, which hits Monferno and makes it scream in pain. Ash responds to this by having Monferno use Flame Wheel, however Paul has Electabuzz use Protect, sending Monferno flying back. Monferno tries Flamethrower, but Electabuzz dodges and executes ThunderPunch. Monferno dodges it in mid-air, and Ash tells it to use Dig. Monferno tunnels underground, and when Electabuzz lands it suffers a direct strike as Monferno emerges. Ash commands another Flame Wheel, and Electabuzz responds with Thunder which heads straight towards Monferno. Ash has Monferno use Counter Shield, and as a result, the Thunder is deflected allowing Flame Wheel to score a direct hit. Reggie is impressed by how Ash is using the momentum to turn the battle around. Ash orders another Mach Punch, but this time Monferno was hit by Electabuzz's Thunder, sending it back towards Ash and forcing it to its knees from both the damage and paralysis. Ash senses something bad and tells Monferno to use Flamethrower, but as he sees Monferno can't launch the attack, he then realizes that Monferno had been paralyzed. Just then, Monferno's tail flame starts to burn more fiercely. Dawn asks if Monferno has activated Blaze, however Reggie explains that the increase in Monferno's flame isn't Blaze, but is actually due to its determination not to be beaten manifesting in its ways. Ash is delighted that Monferno is not giving up no matter what and tells it to use Mach Punch while Paul commands his Electabuzz to use ThunderPunch. The two Pokémon head towards each other full of fury, and both attacks connect at the same time, which causes a massive explosion in the middle of the battlefield. When the smoke clears, Monferno and Electabuzz continue to stare each other down. While Electabuzz is very weak, Monferno has taken far more damage and collapses to the ground, badly injured, to Ash's horror. Olivier rules Monferno as being unable to battle, which means Paul has won the match while Ash, having only managed to knock out two of Paul's Pokémon, has suffered his worst defeat ever.
The sun starts to set on Lake Acuity, as Paul returns Electabuzz to its Poké Ball and Ash cradles Monferno in his arms, telling it that it did a great job. Reggie congratulates Paul on his win, and Paul actually smiles, acknowledging that it was indeed a spectacular battle. Paul promises to send Reggie his Pokémon and bids farewell to him and Olivier before leaving. As for Ash, he is left devastated by this total defeat, almost crying, knowing he was completely outclassed by his rival. And so, the episode ends with Ash holding his badly injured Monferno, with his future in the Sinnoh League and as a Pokémon Trainer left in serious doubt.
- This is the 600th episode of the main anime if Holiday Hi-Jynx and Snow Way Out! are counted.
- All three of the Pokémon Ash used in his battle against Fantina in Shield with a Twist! used Counter Shield in this episode.
- This episode uses Hoenn's Victory Road music as background music.
- The preview for the next episode is narrated by Dawn.
- This is the first episode where Ash loses a Full Battle and his opponent has more than one Pokémon remaining on their team - in this case, Paul had four Pokémon remaining at the end of the battle.
- This is the first time Ash had two evolved forms of starter Pokémon from the same region in the same stage of evolution on hand. They would both reach their final forms later on.
- In fact, it also became the first time he ever had two starters from the same region evolve, as every other time only one starter evolved to a higher level than its base form. The same thing will happen 50 episodes later with his Johto region starters.
- This is the third time that one of Ash's Pokémon has evolved against Paul, with Chimchar evolving into Monferno. The first two were Turtwig evolving into Grotle, and Staravia evolving into Staraptor.
- Team Rocket doesn't blast off or recite their motto in this episode.
- For a split second after Chimchar evolved into Monferno, its eyes were blue then went back to black.