Catching a sweet scent on the breeze, Ash and Pikachu follow their noses to a nearby apple orchard. As Misty and Brock follow, they warn the trainer and his Pokémon against eating apples that don't belong to them. No sooner is this said than Pikachu is caught red-handed with couple of cores! Once Ash proves Pikachu's innocence to the orchard owner, he and Pikachu track down the real thieves, a band of hungry Pichu forced into the orchard due to low amounts of wild growing fruit. Find out how Ash and Pikachu teach them teamwork and help create a symbiotic relationship between the Pichu and the proprietor!
As Ash and his friends continues on their journey, a wonderful aroma fills the air. Ash and Pikachu rush ahead and locate an apple orchard, soon Brock and Misty follow. Pikachu notices that something is eating the apples and watches as the cores fall to the ground. Brock and Misty think Pikachu is the culprit, but he denies it and points at the trees. Everyone looks up, only to see nothing; meanwhile Pikachu catches a falling apple and gets trapped in a net. The orchard owner, Charmaine, arrives believing that she has finally caught the apple thieves that have been plaguing her. Brock immediately begins flirting with Charmaine, and in his lovestruck state he tells her that Pikachu deserves to be punished for his thieving ways. Ash denies that Pikachu is guilty, but Charmaine doesn’t believe him since Pikachu is holding a half-bitten apple in his hands. To prove his Pokémon's innocence, Ash has Pikachu open his mouth and it is revealed that the bite marks on the apple could not have been made by Pikachu due to the shape; they’re too small. Charmaine agrees and apologizes for accusing Pikachu.
Later, Charmaine treats the entire group to a meal. They discuss the fact that it must be difficult for one person to tend to the orchard alone. They offer to help with the harvest, but she declines the offer. However, Brock insists. Soon, everyone has baskets on their back. Charmaine shows the trio that she has strung up noise alarms to keep Pidgey from stealing the apples. Despite this, her apples are still disappearing.
Meanwhile, Team Rocket is hiding in the bushes and Meowth uses a grabbing tool to steal an apple. While the three of them are fighting, a little paw grabs the apple from Meowth and then hands them the empty core. Jessie and James accuse Meowth of eating the apple. They then see a Pichu running off-- it jumps on one of the noisemakers. Jessie, James, and Meowth then flee to avoid being caught.
The others hear the noise and go to investigate. Meanwhile, three Pichu run off with some apples. As the little Pokémon flee, one of them drops an apple with the same kind of bite marks in it as the one that landed in Pikachu's arms earlier. Pikachu tracks down the Pichu and scolds them and then a high-pitched cry is heard. Pikachu discovers a bunch of other Pichu in the bush and that they are under attack by a Fearow. The Trainers find them as the Fearow swoops down. The three bravest of the Pichu jump onto a nearby tree and manage to zap the Fearow. However, they faint after using their attack due to their lack of skill in storing electricity. To make things worse, it was only enough power to stun the vicious bird Pokémon and the Fearow soon recovers. The remaining frightened Pichu huddle up as the Fearow continues to swoop down on them. Fortunately, Pikachu comes to the rescue and drives the Fearow off. It is then revealed why the Pichu are stealing the apples-- there is not enough wild fruit in the forest for the Pichu to eat. Thus the hungry Pokémon were attracted to Charmaine's orchard. Charmaine offers the hungry Pichu a plate of apples, but she is still worried that they will never leave the orchard and continue to eat all of her apples.
Meanwhile, Team Rocket flies over the orchard in their balloon as they try to figure out how to get the apples. While they are discussing this, a nearby flock of Pidgey swoops down to help themselves to the fruit. However, Pikachu directs the Pichu to defend the orchard. They shock the Pidgey and then jump on the remaining ones and attack them with electricity. This drives the Pidgey off, but the Pichu are now exhausted. Charmaine is impressed and once the Pichu recover, Pikachu and Ash continue to train them to help around the orchard in exchange for the apples they have eaten. As shown, the Pichu start gathering apples and putting them in a box for harvest. Charmaine realizes that she can be more efficient in her work now that she has the Pichu to help her. After a bit, Charmaine lets the Pichu take a break and treats them to some apple slices.
While everyone is enjoying their break, Team Rocket appears in their balloon. Ash sends Pikachu after them, but Meowth operates the Rocket Super Sucker device, and its suction cup head holds Pikachu tightly and uses his electricity to power their battery. Team Rocket connects several appliances including a television set and an fan to the battery, as they enjoy their spoils Pikachu is left exhausted from having his power drained. Meowth turns his attention to the apples and proceeds to vacuum them up as well.
The Pichu use Thunder Shock on the balloon and although this stuns Team Rocket briefly, it isn't enough and they soon become fatigued. Meowth then puts the machine in reverse to blow the Pichu away. Ash is about to send out one of his Pokémon, but Charmaine stops him. The Pichu refuse to give up and the group watches in amazement as the Pichu continue their efforts to defend the orchard. Although the air blowing from the machine is strong, the Pichu form a chain until they finally manage to reach Pikachu. Once revived, Pikachu uses Thunderbolt and the attack, combined with that of the Pichu, causes Team Rocket's machine to overload. The surge of electricity destroys the Rocket balloon and sends Team Rocket is sent flying. As the Pokémon celebrate their victory the humans go over to congratulate them on a job well done. Charmaine has decided that she and the Pichu will be partners from now on. In exchange for protecting the orchard, Charmaine will let them have all the fruit they want. By sunset, Ash and his friends say farewell to Charmaine and the Pichu as they continue their travels.
The English title is a reference to the homophonous nature of "corps" and "core", though it is misspelled as "corp". Also, the title is similar to Apple Corps, a company owned by The Beatles that is pronounced as "apple core".