Zigzag Zangoose (Japanese: ザングースＶＳハブネーク！ライバル対決！ Zangoose VS Seviper! Rival Confrontation!) is the 8th episode of Pokémon: Advanced Challenge.
A Zangoose is running past by the gang. May wonders which Pokémon it is. Another one arrives, speaking (human) language. The Zangoose turns to the gang - it is Nicholai, dressed as a Zangoose. He tells he challenged the Petalburg Gym leader - May and Max's father. He didn't win, but he is proud to challenge the Knickerbocker, though May and Max object to believe that their father would wear shorts.
Ash challenges Nicholai to another battle, to which Nicholai agrees. Nicholai puts the Marshtomp costume and sends his Marshtomp. Ash sends Treecko. Marshtomp begins by using Water Gun, but Treecko evades and uses Quick Attack, but Marshtomp does not stop using Water Gun. Marshtomp uses Mudshot, hitting Treecko. Marshtomp uses Iron Tail, but it is disrupted due to Treecko's Bullet Seed. Treecko attacks using Pound, defeating it.
Team Rocket watches the battle and sees Nicholai dressed in Marshtomp costume, identifying him. Still, they want to capture Pikachu, so Jessie sends Jessie's Seviper so that when Ash looks in other direction, Seviper will grab Pikachu. Nicholai changes into Zangoose costume and brings Zangoose. Nicholia orders Zangoose to attack, but Zangoose runs in other direction, feeling something. Zangoose goes in the bushes, so Team Rocket reveals themselves. Zangoose wants to fight Jessie's Seviper. Meowth orders Seviper to grab Pikachu, but stops when he is attacked by Seviper's tail, so Team Rocket roll to a river.
Seviper wraps Zangoose, but Zangoose bites it, so both fall into river. Even in river, Seviper uses Poison Tail, hitting it. Ash sends Corphish and uses Bubble Beam on Seviper. Seviper is hit and Corphish gets Zangoose on shore. Brock made a soup so Zangoose will feel better. Seviper comes to Team Rocket, so James scolds it, but apologises when he sees its mean look. Meowth hears that Seviper wants more battle from Zangoose. Jessie feels same way, she wants to defeat Cassidy once and for all.
Nicholai wants to practice with Zangoose before they battle Seviper. So, Nicholai and Ash dress as Zangoose and Seviper. Ash uses the costume's tail to attack Zangoose. Nicholai is knocked out, but stands up. Ash uses the tail once more, but Nicholai evades, but Ash bites Nicholai. Nicholai thinks there is no way to beat Seviper, but Ash wants him to think how to defeat it. May and Max are sceptical that it will do any good to Zangoose, but Brock says that it is the bond that makes Zangoose stronger.
Skitty goes out of the Poké Ball and plays with Ash. The rest try to catch her, but they hear Seviper coming. Zangoose stands up and goes after it. Jessie and Seviper try to get the Zangoose come to them. It finally arrives, so Seviper attacks Zangoose, but it dodges. The gang supports Nicholai, but an arm grabs Pikachu. The gang goes after James and Meowth, but they stop as Zangoose and Seviper have a battle. Pikachu uses Thunder, but the cage is electric proof. They wait for Jessie to go, but she is staying with Seviper until it is defeated.
They go, leaving Jessie behind, with the gang following them. James brings Cacnea and uses Pin Missile. Meowth and James chant (with Meowth replacing Jessie), but without the end. Ash goes after Pikachu, but is stopped from Cacnea's Sandstorm. However, Ash is throw on James and Meowth, so Pikachu goes off. Zangoose and Seviper fight intensively. Seviper uses Bite, but Zangoose dodges. Seviper uses Poison Tail, but it misses. Nicholai is happy that the training with Ash paid off, but Zangoose is tired.
Seviper is about to finish Zangoose, but Pikachu falls into the middle of the battlefield. The gang and Team Rocket come. They fall on ground, fighting to get Pikachu. When the battle finishes, Jessie's Wobbuffet gets the cage and goes away, so everyone goes after it. Nicholai sees them moving and compares it when Ash was chased by Skitty, so comes up with a plan. Jessie yells, calming everyone down, so Ash gets Pikachu from Wobbuffet's hands. Seviper attacks, so Zangoose retaliates. However, Seviper misses and goes after Zangoose.
Brock notices that Zangoose is doing Zigzag moves. Jessie orders Seviper to use Bite and Poison Tail, but Zangoose jumps. Zangoose uses Crush Claw, defeating Seviper. Jessie praises Seviper for the courage, but Meowth interrupts to get Pikachu. Cacnea is brought out and uses Pin Missile. Pikachu uses Thunder, blasting them off. Nicholai praises Zangoose and thanks Ash on the training. Later, Nicholai battles Ash, sending his Zigzagoon, so Ash sends Pikachu to battle. However, the end is not seen.