Mega-Mega Meowth Madness! (Japanese: ハリマロンVSメガメガニャース！！ Chespin VS Mega Mega Meowth!!) is the 10th episode of Pokémon the Series: XY.
Before heading to Cyllage City, the group decides to stop by the Sycamore Pokémon Lab. Team Rocket decides to kidnap Professor Sycamore, as well as Serena and Bonnie, to pry the professor's mind for the secrets behind Mega Evolution, while Ash and Clemont have to deal with a gluttonous little Chespin with a penchant for macarons.
The heroes head for Cyllage City. Serena suggests they should go to Sycamore first and shows macaraons she baked. Ash, Bonnie and Clemont are interested. Meanwhile, Team Rocket watches a video of how Ash was rescued by Mega Blaziken. Jessie and James plan on stealing Sycamore's info on Mega Evolution and start a Mega Mega Evolution of Mecha Meowth. The heroes visit Prof. Sycamore, who is deligthened to see them traveling together. Serena shows the macarons she baked, so Sycamore's assistant, Sophie, goes to make some tea. After making the tea, the heroes go to eat, but they notice the macarons are gone. They soon see Prof. Sycamore's Chespin took it and eats them. Clemont lets Chespin know it could've asked for some macarons. He asks Chespin to give them back, but gets stung by Chespin's spikes, while Chespin runs off with the macarons.
Team Rocket arrive near the building and see Sycamore playing with the Pokémon. They crash through the glass wall with their truck and Jessie and Meowth exit the truck. Sycamore is startled, allowing Jessie to throw a cube to catch him in a net. Sycamore promises he will not allow them to steal any Pokémon, but Meowth and Jessie admit they came to him, putting him in the truck. Bonnie and Serena sneak into the back of the truck to free Sycamore. However, the truck goes off, so the door shuts and locks itself, so Serena and Bonnie are trapped as well. Chespin sees the truck leaving and follows it a bit. Ash, Clemont and Cosette arrive and see Chespin, who points at the truck. Ash sends Fletchling, who tracks down the truck. As Cosette goes to call Jenny, Chespin finds a trail of macarons Serena left.
Jessie and James open the door of the truck, surprised Serena and Bonnie are here. Serena and Bonnie chant the motto, but Jessie and James stop them. Since Bonnie and Serena resist, Jessie and James tie them up with a tape. Meowth explains they captured them to learn the secret of Mega Evolution and scratches a glass to force the professor to tell them. Everyone is in pain hearing this painful sound, so Sycamore replies he has the data in his pocket. Meowth snatches the memory card containing the data. Meanwhile, Ash and Clemont pass by Meyer, who is told there is a major incident. Chespin stops at the warehouse and Fletchling confirms Team Rocket stopped here. They look through a hole and notice Team Rocket doing something. Chespin sneaks in to find the macaron basket, while Team Rocket loads the data. Chespin climbs up the table to obtain the macarons, but Jessie spots him. Chespin falls down, while Ash and Clemont run into the warehouse.
As Team Rocket chants their motto, Ash and Clemont free Sycamore, Serena and Bonnie. Team Rocket is insulted, but pleased the download has been finished. Meowth climbs into the mecha, while Jessie and James announce the activation of Mega Mega Mecha Meowth. The curtain falls off, revealing the robo-Meowth. Clemont and Sycamore are impressed by their invention, but run out of the warehouse with Ash, Serena and Bonnie. Chespin runs off, but trips over a rock, causing the macarons to fall out of the basket. The robo-Meowth rolls to it, so Clemont jumps off and saves Chespin, who gives him a macaron. Clemont is pleased, but worries about his friends. Pikachu uses Thunderbolt, which the mecha reflects back. Chespin remembers about a wire and shows it to Clemont. As Meowth goes to capture Pikachu, Chespin and Clemont arrive to the beginning of the wire, a plug. Meowth goes to take Pikachu, but the robot suddenly stops. Clemont and Chespin grin, since they unplugged the bot.
Meowth activates the alternate power supply. Clemont sees Chespin's resolve, who uses Pin Missile, but the robot is unscratched. Chespin tackles the machine and repeats it, but it does not affect the robo-Meowth. Pikachu uses Quick Attack to help Chespin, but it still is not enough. However, Mega Blaziken appears, hitting the robo-Meowth hard. Mega Blaziken uses Flamethrower, bruning and destroying the machine. Pikachu uses Electro Ball and Chespin Pin Missile on the power source, causing the robot to explode, as well as making Team Rocket blast off. Ash and Clemont are glad for Mega Blaziken's support. Clemont approaches Chespin and gives it macarons. Chespin is happy, though shares the macarons with everyone. Mega Blaziken's trainer, Meyer, considers traveling with Serena and Ash to be a beneficial experience for Clemont, who will learn more.
Sycamore thanks the heroes for the help and tells them he will have the lab repaired in no time. Before leaving, Bonnie informs Clemont Chespin has been watching him the whole time. Clemont thanks Chespin, though Sycamore considers Chespin to be willing to travel with Clemont. Clemont understands this and asks Sycamore for the Poké Ball. Sycamore gives it to him, so Clemont calls Chespin into its ball, who is happy to know it will travel with Clemont. The heroes run off, bidding Sycamore farewell.
- "Who's that Pokemon?": Chespin (US)
- "Pokemon Quiz": Chespin (JP)
- Blaziken Mask is revealed to be Meyer, Clemont and Bonnie's dad.
- During the explosion of Mega Meowth, Chespin's visible arm is lighter than usual.