A Mudkip Mission (Japanese: 秘密の池！ミズゴロウがいっぱい！？ The Secret Pond! Full of Mudkip!) is the 25th episode of Pokémon: Advanced.
Get ready for a new episode of May's Expedition as she, Ash, Max and Brock stumble upon a swamp. There they find the swamp full on Mudkip and their caretaker, an elderly man named Old Man Swamp (or Mr. Swampy) who has the same whiskers as a Mudkip's fins. He explains that he gets Mudkip eggs from the Hoenn League and when they hatch they wait till their old enough to give to Professor Birch. But Team Rocket also has plans for the Mudkip. What evil will they have in store for them, and will Brock get a new friend?
May leades an expedition where they follow the river. They stop near a waterfall. Brock throws rope and his Lotad uses Water Gun to get to higher level. May gets first and helps them - she used Silcoon to get up. They go further, as they enter a swamp.
The gang encounters Mudkip, spotting some babies. May is happy she does not have one, as the last one attacked her. May goes to catch a Mudkip (since their inhabit is unknown), but a Mudkip uses Water Gun, stopping her. One Mudkip falls into water and the current leads to the Waterfall, so Lotad goes to help it. Even Lotad can't get to shore, so another Mudkip helps them.
A man appears, making May and Ash think it is a monster. The man mistakes them for stealing Mudkip. The man introduces himself as Swampy and is quite amazed that they climbed the waterfall so they can practice. Swampy forgives them, since they saved Mudkip. They go to Swampy's house for tea. Brock spots some blue things - it are Mudkip eggs. Brock asks him where he got the eggs, so Swampy gives them a question - what happens if there are two Pokémon with same level.
Nobody knows, so Swampy replies that he raises the Mudkip from eggs to adults. Max says that Brock will be a breeder and Swampy offers him that he will see the Mudkip hatching from eggs. A Mudkip hatches from an egg and splashes May with water. Brock mentions that a Mudkip saved another one - Swampy knows that it is the wild and bigger one, the one he didn't raise.
Team Rocket searches for "twerps" and they stumble onto a fence. James explains that the fence protects the intruders from passing, so they bring Cacena and Seviper. Seviper uses Poison Tail, but with no effect. Cacnea uses Needle Arm on James, making him break the fence. Wobbuffet gets out of the Poké Ball, making it move a rope - Swampy hears the cans that have been tied to it, so he goes to look. May, Ash and Max go with him, but Brock finds the Mudkip who gets away, so Brock tracks it.
Brock finds the Mdkip and offers it his food, but it refuses to eat. Swampy, May, Ash and Max came to the fence, finding it destroyed and the cans stomped. Team Rocket appears. Swampy (unintentionally) tells everyone that Mudkip are rare and that if the dam were to break, the Mudkip would go away. James brings Cacnea again and it uses Needle Arm, but on James. James is thrown against the dam, breaking it.
Brock is still offering food to Mudkip, but he sees a giant wave coming, so he brings the Forretress and uses Rapid Spin to stop the wave. Lotad brings the baby Mudkip to the shore and Brock and the larger Mudkip the rest. Brock praises everyone, but spots one lone Mudkip left. The larger Mudkip gets the smaller one, but the stream is strong, making it go to the waterfall. They fall, but they are left hanging on a rock on a waterfall.
Brock ties himself with the rope they used to get on higher level and goes to Mudkip. The Mudkip does not trust Brock much, but is convinced and gives Brock its tail. The gang pulls Brock upwards and rescues them. However, more trouble arises as Team Rocket cleaves the woods from the swamp and taking the Mudkip with them! Brock remembers that the ground is quite soft and orders Mudkip and Lotad to use Water Gun to soften the ground even more.
Team Rocket's machine begins to sink into the earth. Mudkip pounds the bag, freeing the Mudkip. Pikachu uses Thunderbolt to blast Team Rocket away. Swampy proposes that Brock should take the Mudkip, since the other Mudkip will go away. Brock convinces Mudkip and it is happy to go with Brock as his new friend.
- From this episode, Brock, May and Ash own all three Starter Pokémon - Torchic, Mudkip and Treecko.
- Featured Pokémon: Pelipper