On their way to the Grand Festival, the gang stops at an island filled with berries. May decides to make Pokéblocks, but no one except a wild Munchlax likes it. When Munchlax is blamed of eating everyone's Pokéblocks, May decides to prove them wrong and capture Munchlax.
The gang is going to Slateport City. During their travels, they spot a lot of berries. Ash gets one and eats it, only to have its mouth burned by its spice. At the Pokémon Center, Nurse Joy is terrified, thinking Ash is a monster with his big lips. Brock, as always, flirts with her, so Max pulls his ears. The gang wants Joy to look after their Pokémon, so Joy accepts this duty. Ash goes away to practice Snorunt's Ice Beam. A group of children pass by, planning to make Pokéblocks.
Nurse Joy tells them that there are many kind of berries, so they kept the blenders inside the Pokémon Center. May goes away, experimenting. Meowth, Jessie and James are tending the plants. Meowth is exhausted, so Jessie and James threaten him to work, as they are out of money. Jessie and James also lie down, seeing the clouds. Suddenly, a Pokémon stomps on their bellies. It is a Munchlax, so Team Rocket demands that it apologises, but it doesn't. As they go to get it, they see some Berry blenders inside the Center. Meowth has made a plan and tells it to Jessie and James, who agree with him.
Snorunt uses Ice Beam, but before it hits the target, it fails. Snorunt tries again, but it goes up and down to Ash. Ash unfreezes himself and his lips are back to normal. Inside, Brock and Max spot the people mixing the berries. Joy comes and tells them the best way to know which Pokéblock is the best is to experiment. Joy tells them they are welcome to grab any berries to make the Pokéblocks. May arrives with a basket full of berries. Brock tells her too much or too little berries can ruin the effect, so gives her the cookbook Natalie gave to him. However, May tells him she got a recipe of her own.
She calls it "May's purple surprise". May cuts the berries and blends them. The Pokéblocks come out and Brock and Max eat them - the result is a bit catastrophic, making May angry. Meanwhile, Snorunt uses Ice Beam. Ash is not satisfied, as there needs more power, but gets hit by one of them. When he unfreezes himself, he calls it for a day. Munchlax smells something and gets inside the Pokémon Center. Inside, the gang's Pokémon taste "May's purple surprise" - the result is that all Pokémon are terrified by the taste, so are called back. May is unmotivated, though Joy tells her she needs to experiment more. Soon enough, they spot the Munchlax, who eats all Pokéblocks. May is happy and goes to make more.
Team Rocket, disguised as PokéBlock tasters, appears. They tell them they are here to improve the recipes. May plans to give them her purple surprise. Meowth and Wobbuffet sneak to steal the PokéBlocks. Team Rocket tastes the berries and May gives her own. The conclusion of "May's purple surprise" is that it should be destroyed. However, Jessie likes the Pokéblock. Soon, the children see their Pokéblocks are gone. Everyone begins to suspect Munchlax ate it, though May stands in its guard. Jessie and James tell May it is definite Munchlax ate the Pokéblock and is going away. Munchlax is seen eating the berries outside the Pokémon Center.
May tells them they did not see Munchlax eating the Pokéblocks and it ate a lot of May's purple surprise, but this fact goes to wind as she sees Munchlax eating berries. May still does not give up on defending Munchlax - she has set her mind on capturing it. The children agree, although they think it still is not fair. May sends Combusken, but Munchlax is gone. They see it on a tree, eating more berries. May offers her purple surprise, to which Munchlax is interested into. Combusken uses Fire Spin, but Munchlax is standing behind May, asking for more of her Pokéblock.
May gives it a final Pokéblock and Combusken uses Sky Uppercut, but surprisingly, it evades. Combusken hits is head and it is revealed Munchlax went for a nap. May goes to wake it, so gives it another Pokéblock. Munchlax is ready to battle, so Combusken uses Sky Uppercut, but Munchlax evades again and Combusken hits its head. Munchlax eats another berry. Team Rocket is seen mixing berries, so Jessie plans to steal Pikachu as well. James goes to eat one last berry, which is the same berry Ash ate before, so his lips are on fire and goes away, near the gang. Joy suspects he is fake and they all see the Pokéblocks falling from James' bag. Jessie grabs Pikachu in a moment and they take off their disguises.
They go away in the balloon, so Combusken uses Fire Spin, freeing Pikachu. Pokéblocks begin to fall, so Munchlax eats them and goes to the balloon. Munchlax and a bag fall down, so May catches Munchlax. Ash sends Snorunt to use Ice Beam, but the attack goes up, hitting a tree instead. Team Rocket intimidates them, as they have one bag left, but the balloon is popped by an ice spike from the frozen tree. Team Rocket is blasted off and Munchlax begins to eat the fallen berries. May throws the Poké Ball, but Munchlax eats it. However, it has been captured inside!
- Although Munchlax ate the Poké Ball, it got captured, unlike Sullivan threw Master Ball on Whiscash.
- This episode's name is a pun to the statement "Very, very interesting..."
- This episode was the first to feature a Generation IV Pokémon, which was Munchlax. Munchlax did make an appearance in the seventh Pokémon movie, but this was the first episode to feature this Pokémon. In this episode, May's Purple Surprise, a Pokéblock which is enjoyed by Jessie and Munchlax only, is introduced in this episode, as well as the intense spiciness of the Tomato Berry.
- Once again, Mime Jr., Lucario and Weavile have been removed from the intro.
- Featured Pokémon: Eevee, Bagon, Espeon, Vaporeon.