It's a beautiful day at Lake Acuity and Ash, Dawn and Brock, fresh from their adventures in the Snowpoint Temple and aboard the Ampharos Train, have finally arrived for Ash's Full Battle against Paul that Reggie suggested they have ten days earlier. As Ash looks out at the gorgeous view, Dawn recalls the legend the gang heard about during the Wallace Cup that says the legendary Pokémon Uxie lives in Lake Acuity. Ash likes the thought of Uxie watching his battle with Paul, and the gang head for the nearby Pokémon Center where they are due to meet Paul and Reggie.
Ash hands in all of his Pokémon to be checked over by Nurse Joy and Brock begins to flirt with Nurse Joy until he's taken down by not just Croagunk's Poison Jab, but also with Chansey's Pound. Nurse Joy apologizes for her overprotective Pokémon as Croagunk drags Brock away. Ash learns that Paul has already arrived, and quickly heads out for the Center's battlefield.
Outside, the battlefield isn't in a usable condition as it's mostly a pile of rubble and working construction is none other than Team Rocket. They recite an alternate version of their motto, which is centered around their new jobs. Suddenly Ash arrives and he nearly sees through their disguises after they call him 'twerp'. It turns out the battlefield is out of commission for a few days due to overuse. Ash begins to worry as he doesn't know where to meet Paul until a referee named Olivier arrives, having being asked by Reggie to officiate the Full Battle. He tells Ash that as the regular battlefield can't be used, Reggie has selected another location.
On a clearing beside Lake Acuity, Paul is practicing with Electabuzz under Reggie's watchful eye. Reggie notes how well Paul has polished his Pokémon's moves since the battle against Brandon, prompting Paul to ask Reggie why exactly he suggested the Full Battle in the first place. Reggie explains that the battle against Brandon had a major effect on Paul, making him realize it was the perfect time for a Full Battle between him and Ash.
At the Pokémon Center Ash picks up Pikachu, Staraptor, Grotle, Chimchar, Buizel and Gliscor who are all ready and willing to battle Paul, Chimchar especially so. Brock reflects on Cynthia's words back in Celestic Town, when she told Chimchar it had a bigger and better destiny. Brock knows that Chimchar is at the very center of Ash and Paul's rivalry, and that Chimchar will be instrumental in what happens between them. And so, with everyone ready to go, Ash goes out to meet Paul and Reggie.
At the lake front, Reggie thanks Ash for coming and explains that part of the reason that he asked for the battle is how alike Ash and Paul are. Both are intent in growing strong alongside their Pokémon, only their training methods differ. He tells Ash that a Full Battle between them is inevitable, and it's a good time for them both to compare each other's strengths and weaknesses. Just then Olivier arrives in a balloon with a portable scoreboard. Helping him man the scoreboard and make the necessary changes as the match progresses are Team Rocket, once again wearing disguises.
Olivier officially states the rules; the battle will be a Full Battle, six-on-six with substitutions freely allowed on both sides. Coin Toss is used to decide who gets to pick their Pokémon first, and Ash wins. He sends out Buizel first, and Paul sends out his Torterra. The referee begins the match, only for Ash to instantly recall Buizel, similar to how Paul recalled his first Pokémon during the match against Brandon when he didn't like the type-matchup. Ash apologizes to Buizel and promises he'll call on it soon, and sends out Gliscor to replace him. Ash reminds Paul that he encountered Gliscor before when it was still a Gligar but Paul remains silent, choosing not to engage in conversation with his rival.
The battle then begins properly as Ash orders Gliscor to use Sand-Attack, and Gliscor sends a lot of sand towards Torterra, clouding its vision. Reggie commends Ash on the smart move, as Brock notes that Ash has seen Torterra in battle before and therefore knows many of its strengths. Paul orders Giga Drain. However, the energy-sapping tentacles plunge into the ground, missing a now flying Gliscor completely. Brock and Reggie agree that Paul probably intended Giga Drain to miss to try to lull Ash into a false sense of security and let down his guard. Ash then has Gliscor use X-Scissor on Torterra and it scores a direct hit. Being a Bug-type move, it causes a fair bit of damage against Torterra, but not enough to cause it to faint.
Paul then starts to battle directly and orders Frenzy Plant, the most powerful Grass-type move as well as a risky one. Luckily, Gliscor is fast enough to avoid the vines, and Torterra is left immobilized while it recharges. Ash knows he has an opening and has Gliscor use Fire Fang which hits Torterra, and Ash has Gliscor follow this up with another X-Scissor. Ash decides to go in for one more hit and has Gliscor use Steel Wing, but as Gliscor heads towards Torterra it recovers from Frenzy Plant and Paul has it use Crunch. Although Steel Wing hits, Torterra bites on to Gliscor's tail, and Gliscor struggles, but is unable to break free. Paul then has Torterra use Giga Drain, and this time it hits dead-on, sapping Gliscor's energy while recharging its own. Reggie and Brock realized this was part of Paul's strategy, to allow Torterra to be immobilized so Ash would go in close-range. Gliscor is still struggling to break free from Giga Drain and Ash has Gliscor use Fire Fang on the energy tentacles, which hurts Torterra and sets Gliscor free. Both Gliscor and Torterra are left exhausted, and Ash decides to recall Gliscor for some rest. Dawn is very nervous just watching the match, and Ash notes that despite its fatigue Paul has chosen not to recall Torterra and sends out Staraptor to battle next. Reggie realizes that Staraptor is the Staravia he battled back when Ash was in Veilstone City, and Dawn tells him that Staraptor defeated Honchkrow in a PokéRinger competition not too long ago, which impresses Reggie.
Ash has Staraptor begin with Brave Bird, and Staraptor moves in for the hit. However, Paul has Torterra use Stone Edge. The pointed stones score a super effective hit and Staraptor is sent plummeting to the ground. Now everyone is aware that Paul left Torterra in because he knew Ash would switch to Staraptor, and now that it has done its job Paul recalls Torterra to its Poké Ball. Reggie asks Brock and Dawn if Ash came up with any kind of strategy against Paul or if he switched any of the Pokémon in his party. Dawn tells Reggie that Ash planned on using his usual six from the start while Brock tells Reggie that with the exception of Pikachu, Ash's Pokémon were all acquired by him since he came to Sinnoh. Reggie tells Brock that as Paul has battled Ash before and knows what Pokémon he has, and based his team on that information.
Paul's second Pokémon is Weavile, and after making sure Staraptor is OK to battle Ash tells him to begin with Quick Attack. Staraptor gets the hit in, and Paul then has Weavile use Swords Dance. Dawn asks what Swords Dance does, and Reggie explains that it increases Attack power, making Weavile far stronger than normal. Ash calls for an Aerial Ace, and Paul counters this by ordering Blizzard. The Ice-type move hits Staraptor hard, and Paul then has Weavile use Metal Claw. Staraptor flies low and Weavile jumps onto his back, shocking everyone. Weavile then slashes Staraptor's back and jumps off as the Predator Pokémon crashes to the ground. Paul orders Weavile to go after Staraptor with another Metal Claw, and Ash has Staraptor use Close Combat. Staraptor and Weavile trade blows, but Staraptor is able to gain the advantage and sends Weavile flying, having suffered a lot of damage from the Fighting-type move. Staraptor maintains the assault, and Paul orders a Blizzard while Ash calls for Brave Bird. Staraptor flies out of range of the Blizzard and scores a direct hit with Brave Bird. Although Staraptor suffers from the recoil, Weavile comes out of it far worse off and after despite its efforts collapses to the ground unable to battle. Olivier rules Weavile as out of the battle and Ash, now with the advantage, commends a battered Staraptor on a fantastic performance but knows better than to get too confident over this win. Ash also knows that Staraptor took a real beating and recalls it for some rest.
Paul sends out Electabuzz next while Ash sends out Grotle. As Electric-type moves don't work very well against Grass-types, Ash doesn't know what Paul is thinking and has Grotle use Energy Ball. Paul has Electabuzz use Light Screen and Electabuzz sets up a barrier which the Energy Ball smashes against, instead of getting a direct hit. Brock explains to Dawn that a Light Screen helps to defend against special attacks like Energy Ball, cutting down their power by half. Now the Light Screen is set up, Paul substitutes Electabuzz with Honchkrow, a much better type-matchup against Grotle. Brock tells Reggie that Grotle battled against Honchkrow before, and it was that battle that caused Turtwig to evolve. Grotle is determined to defeat Honchkrow to make up for the defeat it suffered after evolving, and Ash decides to leave it in, determined to show Paul and Honchkrow how much Grotle has improved since then. Everyone else knows this is a huge mistake on Ash's part due to the disadvantage as a Grass-type, especially Paul.
Night Slash is used by Honchkrow after a missed Razor Leaf, and although Grotle tries to stand up to it the hit is still powerful. Ash orders Grotle to use Energy Ball, however Honchkrow is shielded by the Light Screen making him and Dawn realizes that Light Screen can be passed on to other Pokémon. With the type-advantage and the Light Screen, Brock tells Dawn that Paul is trying to overwhelm Ash as Honchkrow is told to use Haze which surrounds Grotle. Normally when Paul battles, it's to polish up his Pokémon's moves or to increase their power but he has a different motive during this battle. Paul is going for the win. Reggie explains that Paul has worked out Ash's battle style which is allowing him to keep the pressure on Ash. When Grotle gets Night Slashed again, Ash sees that it is exhausted by now, so he has it use Synthesis. As Grotle regains its energy, Paul takes advantage of the moment and tells Honchkrow to use Sky Attack. Honchkrow begins glowing and makes a direct line for Grotle. Ash has Grotle use Rock Climb to try to counter, and the attacks collide, obscuring both Pokémon, however Honchkrow flies clear while Grotle has been knocked out. Olivier rules Grotle as being unable to battle, and Ash recalls it as Paul recalls Honchkrow. Reggie, noting on Ash's poor judgment, points out that using Synthesis as healing moves have the disadvantage of leaving a Pokémon open to attack and a Trainer should make note of the opponent's condition before using one or be an easy target. Brock concurs, knowing that Ash wanted to have Grotle defeat Honchkrow so bad, it clouded his judgment.
Both Trainers must select new Pokémon, and Pikachu lets Ash know he's ready to go up next. Ash can see his partner is determined to help defeat Paul and sends him into the battle. Paul sends in a Pokémon that surprises everyone, Magmortar, evolved from his Magmar. With one of his Pokémon down, and feeling the pressure piling on, Ash prepares to take on Magmortar.