BW064: Crisis at Chargestone Cave!

Episode Plot
After Ash beat Clay and got his Quake Badge, Ash and co. decide to head to Mistraltin City next. Cilan says that to get there they have to get through Chargestone Cave. When they got there, Ash notice Pikachu was beyond tired. The reason was that a Joltik was feeding off Pikachu's electricity, and he's not the only one the Joltik are feeding off, Iris' Emolga and Cilan's Stunfisk (being part electric) are being drained too. And who should they run into but their old friends, Bianca and Professor Juniper, who explains the situation. What could be causing the Joltik to leech off of other Electric Pokémon?

Pokémon Debuts

 * Crustle