Chargestone Cave is a cave which is literally charged with energy, causing the rocks within to levitate in the air. It connects Route 6 to Mistralton City. When leveled up here, Nosepass and Magneton will evolve.
You won't be able to pass through the cave until you've beaten Clay at the Driftveil City Gym, as his Pokémon will smash the Galvantula web blocking the entrance.
When you first enter the cave, you'll meet the Shadow Triad. They lead you to N, who says that Team Plasma are waiting to test you. Afterwards, Professor Juniper arrives with Bianca in tow acting as her bodyguard. The Professor reveals she's here to study the Klink in the cave and gives you a Lucky Egg.
After you've travelled through the cave you'll find N near the exit and have to battle him. Once you've defeated him, Professor Juniper and Bianca come along, much to N's disgust. He appears to have a problem with Juniper because of her research, and leaves the cave. The others exit soon after, and you're free to continue your journey.
Chargestone Cave debuted in The Lonely Deino! during a flashback, as the trainer of the Deino Iris cared for in the episode recounted getting lost in it trying to catch a Tynamo.
The cave was the focus of Crisis at Chargestone Cave!, where Professor Juniper was doing research. The resident Joltik and Galvantula that lived there were consuming all of the electricity in the vicinity, even kidnapping Ash's Pikachu and Bianca's Minccino. It was later revealed in the episode that the Team Rocket Trio was taking rocks from Chargestone Cave, which serves as an energy source for all the Pokémon that live there, and forced the Joltik and Galvantula out of the cave. Ash and co. eventually drive the villains away from the cave (causing Dwebble to evolve in the process) and the cave was once again safe for Joltik and Galvantula to live in. It reappeared in Evolution Exchange Excitement!, where Ash and his friends found a group of Klink and a Klinklang that were angered by a pen that was stuck in one of Klinklang's gears (which was later revealed to be caused by the Sunglasses Krokorok. It made a very brief appearance in Explorers of the Hero's Ruin!.
