Gulpin it Down (Japanese: ゴクリン撃退大作戦！ The Great Gulpin Repelling Strategy!) is the 25th episode of Pokémon: Advanced Challenge.
During their break, the heroes get their lunch eaten by a Gulpin. They soon find out a group of Gulpin is eating away the food supplies in the city. They contact Nurse Joy and Officer Jenny, who receive help from Professor Jacuzzi, who decides to stop the Gulpin. After driving off the Gulpin, the professor uses a machine to launch Gulpin away. However, the machine malfunctions and oversizes Gulpin and Ash's Treecko, who battled the former.
As the heroes have lunch, Brock notes they are quite close to Petalburg City. Ash is excited for his battle against Norman, but Max reminds him his father is quite strong. May and Max start imagining what will they eat when they get there, seeing their mom makes a lot of good meals. May goes to grab a sandwich, but a Pokémon takes it before she does. The Pokémon gulps Max, Ash and Brock's food and even spits out Pikachu's dish. The heroes are surprised how Gulpin ate all of their food, but May remarks it looks cute. A distress signal is heard, as everyone must evacuate from their homes. Some moments later, the heroes walk the streets and do not see a single person nearby. Suddenly, a woman screams, as the Gulpin are eating her bread supply. Ash's Pikachu comes to help, but the Gulpin overwhelm him. Ash pulls Pikachu out, who has fainted, while more Gulpin fall from the vents. Officer Jenny arrives and her Tangela uses Vine Whip to pull the woman and the heroes out. Officer Jenny points out they must evacuate and decides to take the heroes to a place, where they can rest.
Jenny brings them to the Pokémon Center, where Nurse Joy oversees the situation. Brock is amazed Officer Jenny and Nurse Joy are working together, making him blush, but Max prepares to punish him. Ash notices this looks like a different Pokémon Center and is told it is a "Gulpin Defense Center". An older man, whom Jenny introduces them as Prof. Jacuzzi, points out the Gulpin population is rising once again. The Gulpin each year eat everything and Prof. Jacuzzi is certain they are headed for the center of town, where they would eat the rest of the food this town has. Jacuzzi already has a plan to stop them, but the Gulpin are going towards the town's center. On the bridge, the heroes, with Officer Jenny, wait for the Gulpin, who are coming. Jacuzzi launches a rocket, revealing a giant PokéBlock for Gulpin. The PokéBlock attracts Gulpin, who are trying to eat it. Jacuzzi presses a button, causing the PokéBlock to fly away, so do the Gulpin as well. However, Team Rocket takes the PokéBlock, claiming it as their own. The Gulpin attack the balloon using Sludge, causing the balloon to descend down. Next, the Gulpin use Stockpile, then blast Team Rocket off by using Spit Up.
This causes the PokéBlock to fall down, and as Brock catches the PokéBlock, Gulpin go after it. Officer Jenny sends Meganium, Tangela and Parasect: Tangela uses Vine whip, Meganium Razor Leaf and Parasect Stun Spore to hold the Gulpin off. Ash sends Treecko, who dodges Gulpin's Sludge and uses Bullet Seed, hurting the Gulpin. Jacuzzi presses a button for the PokéBlock to fly off, with the Gulpin following it. The heroes are glad the Gulpin are gone, but Jenny is certain they will return back. Team Rocket is wandering and are hungry, but Jessie's Wobbuffet spots Gulpin leaving, who ate the PokéBlock. Team Rocket decides to go after Gulpin in search for food. During the night, another signal is heard and the lights go off. Nurse Joy reports an underground cable was cut and switches to a backup generator. The Gulpin are headed for the town's center, with Team Rocket following them. Nurse Joy presses a button to seal the gates, forcing the Gulpin to go above ground. Jacuzzi is uncertain what to do, since the Gulpin won't fall for the PokéBlock trick twice.
The Gulpin emerge out of the sewers, so Jenny sends her Pokémon to battle. Officer Jenny's Tangela, Meganium and Parasect, along with Ash's Pikachu, attack. Nevertheless, more Gulpin are going towards them and are forming a line. Professor Jacuzzi arrives and activates a machine, so Gulpin disappear in a purple light, as Jacuzzi fires the Gulpin out of his vehicle, via a cannon. More and more Gulpin are absorbed to be fired away, amazing the heroes by this plan. One is left and as Jacuzzi goes to fire the beam, the machine stops working. The Gulpin is trying to go away, but Ash sends Treecko to battle it. Treecko uses Bullet Seed, but collides with Gulpin's Sludge attack. Jacuzzi has enabled the machine to work, while Treecko uses Pound. At same time, Jacuzzi fires his cannon. Inside the machine, Gulpin attacks with Stockpile and Spit Up, so the machines are broken. Jacuzzi attempts to repair, but the machine is destroyed. Two purple lights emerge; Gulpin and Treecko are freed, but are the size of buildings.
May fears they evolved, but Max assures her they didn't. Jacuzzi explains Gulpin's attack affected the machines, causing this error. Gulpin moves, so Treecko comes to stop it. People evacuate the area and as Treecko throws away Gulpin, Gulpin retaliates with Sludge. Per Ash's order, Treecko throws Gulpin in the lake. Team Rocket are going away with food they got, but when Gulpin flies over them, it attacks with Stockpile and Spit Up, blasting them off and dropping their food down. Gulpin uses Stockpile and attacks with Spit Up, but Treecko dodges the attack. As Treecko dodges, he shrinks down to his normal size. Ash calls Treecko back, but Gulpin tries to go into the town again. May proposes to catching it, for despite its size, Gulpin still is a Pokémon. Jacuzzi throws his Poké Ball, but Gulpin frees itself immediately.
Instead, Nurse Joy gives Jacuzzi a Heavy Ball, while Brock points out it is perfect to catch heavy Pokémon. Jacuzzi throws the Heavy Ball and captures Gulpin. Brock wonders if Gulpin would be still oversized, but Jacuzzi says that it shrinks to its own size. He sends it out, but soon calls it back, since it is still enormous. Nevertheless, Jacuzzi promises to work on returning Gulpin to its original size.
- Featured Pokémon: Larvitar, Treecko, Carvanha, Shedinja.
- At the beginning of the episode, a classic Pokémon identification can be seen. In this episode, the Pokémon is Magmar.
- This is the last episode in which Officer Jenny is voiced by Lee Quick.
- The title of this episod may be a pun of the sentence "gulp it down".