A Six-Pack Attack! (Japanese: オーキド博士とオダマキ博士！秘密基地の戦い！！ Prof. Oak & Prof. Birch! Secret Base Battle!!) is the 31st episode of Pokémon: Advanced Challenge.
Ash sees his newest badge he won from Norman. He asks Brock where is the next Gym, so Brock tells him in Fortree City. However, Max and May remind him they need to see Prof. Birch first. They arrive in front of his lab, but a car goes past them, nearly crashing itself. The driver is Prof. Birch - he drove fast to meet Prof. Oak when he forgot to do it. Ash and Brock go with Birch while May and Max will stay in the lab for a while. Max is exceptionally happy to meet Prof. Oak in person.
While driving, Birch sees a Skarmory on a peak. While greeting it, he loses his sight of the road when a farmer passes. Fortunately, they pass him, however, the man seems somewhat familiar... At the lab, Max and May see the new Starter Pokémon with Birch's assistant. May remembers the day she got her Torchic, but Max annoys her so she goes after him. Max bangs into a man - it is Prof. Oak! Max is amazed to meet him, so he shows photos of Oak in the magazine he got. Oak makes an autograph for Max. Oak wonders where Ash and Brock are, so Birch's assistant says they got onto Birch's car and they drove down to the town to pick him up, but Oak went up, assuming Birch forgot about him.
Max wonders which Starter Pokémon are in Kanto, so Oak sends his own - Bulbasaur, Squirtle and Charmander. Team Rocket oversees the event, so Mewoth thinks if he got all the six Pokémon, he'll be happy to have them as friends... Max is pleased to see Bulbasaur and touches its back, but Bulbasaur gets angry and tackles him. He goes to see the other two Pokémon, but Squirtle uses Water Gun and Charmander Ember when he touches them. Oak is amused, so he tells Max that he learned their attacks in a similar way. Bulbasaur wants to meet Max, so she shakes its vine. They see a giant Skiploom approaching them - it is Team Rocket.
Team Rocket steals all the Starter Pokémon, so May, Max and Oak go to save the Pokémon. Meanwhile, Ash, Brock and Birch wait for Oak, so Birch calls his assistant Joshua. He hears that Team Rocket has gone with the Starter Pokémon, so they need to after them as well. Oak knows that they did not just wander off so easily in a giant Skiploom and he notices something behind the waterfall. It is a cave, so they venture within. Joshua shows Birch Max's backpack, so they drive off, taking the bag.
Oak, Max and May sneak, but accidentally Oak goes through the laser, closing the main door and warning Team Rocket. They see the Pokémon and go after them, but fall into a hole. May goes to bring her Pokémon, but the Poké Balls are sucked into the vacuum cleaner and Team Rocket wanders off with the Pokémon. Birch drives quickly to the base (even if they aren't on the road). Max thinks he might be small enough to squeeze through the bars, but Oak asks if he can borrow his photos. Team Rocket celebrates, but James thinks they should see the captives. Meowth shows on camera they have nothing to worry about, even if a picture of Oak is displayed, fooling them.
Max squeezed through the bars and needs to free the Pokémon. Max needs to order the Pokémon to use a Fire, then a Water Attack and Tackle to set them free. Torchic and Charmander use Ember, followed by Squirtle and Mudkip who use Water Gun and, lastly, Treecko uses Pound and Bulbasaur Tackle to destroy the bars. The Pokémon are free. Birch whistles and a Poochyena appears. Poochyena smells Max's backpack and runs towards Max, so Birch, Brock and Ash follow it. The Pokémon free Oak and May, so they need to get May's Poké Balls back. May sees them partying, so Oak proposes a tactic. Team Rocket hear Zubat's Supersonic to distract them, while Bulbasaur gets May's Poké Balls.
They all go towards the entrance, but find it closed. An alarm is heard - Team Rocket sees them at the entrance and photo of Oak falling over. Meowth presses a button to seal them. Dugtrio appear, so they go falling through the tunnel. At the end of it, there is a lake with a sleeping Gyarados. Team Rocket go furious when they see Max, May, Oak and the Pokémon escaped through the hole. Team Rocket falls down as well, even if Jessie and James argue near the Gyarados. Gyarados wakes up and attacks them using Hydro Pump.
When they follow the Poochyena, Birch spots that Zubat live outside and Poliwrath in the lake (normally Poliwrath live near the waterfall and Zubat inside the caves). They arrived near the waterfall - the entrance of Team Rocket's base. Meanwhile, May, Max and Oak go towards the exit, but see it is sealed. Max yells through a small hole and Poochyena goes after the source. Ash, Brock and Birch hear Max's voice, so they need to free them. Oak studies the door and realizes they need to attack using a combination to destroy the door. They need to use Water attack and then Thunderbolt.
Brock sends Lombre and Mudkip - they use Water Gun on the door, with Pikachu following with Thunderbolt. Afterwards, May's Skitty, Squirtle, Mudkip and Bulbasaur tackle and Treecko pounds the door, releasing themselves. However, Team Rocket turn the Skiploom machine on and try to capture the Pokémon. Pikachu uses Thunderbolt, but with little effect. Lombre and Mudkip attack with Water Gun, but with little difference. To destroy it, they need to use a combination of attacks.
Charmander and Torchic use Ember, Mudkip and Lombre Water Gun and Skitty Blizzard - cracking the machine. Pikachu uses Thunder, destroying the machine and blasting them off. Anyway, the gang is seeing to leave Oak and Birch to go to Fortree City.
- Featured Pokémon: Slowking, Jolteon, Nidoqueen, Makuhita
- At the beginning of the episode, a classic Pokémon identification can be seen. In this case, it is a Clefairy.
- May befriending Professor Oak's Bulbasaur and Squirtle appears to foreshadow the capture of her own members of both species later on in the series (one of which would actually be intended to be a starter).
- When Team Rocket is seen blasting off, Jessie, James, and Meowth form the letter "R".