After Ash beat Clay and got his Quake Badge, Ash and co. decide to head to Mistralton 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 and Galvantula to leech off of other Electric-type Pokémon as well as electricities from the Pokemon Center?
This is the second episode in a row to feature the evolution of a main character's Rock-type Pokémon, with Cilan's Dwebble evolving into Crustle (Ash's Roggenrola evolved into Boldore in the last episode).
It is revealed that Bianca's Minccino learned Thunderbolt.
This is the second time Ash looked up Galvantula on the Pokedex when they're outside the entrance of the Pokemon Center after draining electricity. First was BW017: Scraggy-Hatched to be Wild but when he looked it up on Pokedex, the image picture of it is not in the scene and the difference is, it said "the evolved form of Joltik" which Ash looked it up first in BW031: Oshawott's Lost Scalchop! while searching for his Oshawott's Scalchop.
Ash and co. (minus Bianca) may have encountered swarms of Galvantulas first and one Joltik, but this is worse when they're living together in many groups.
Professor Oak's Live Caster: Beheeyem
Who's That Pokemon?: Dwebble (Japan), Galvantula (U.S.)
Chargestone Cave makes it second appearance since in the flashback scene of Deino's trainer trying to find a way out in BW058 The Lonely Deino.
The soundtrack title theme used was actually from the same movie of Zoroark: Master of Illusions when Iris and Cilan stopped Team Rocket's vehicle before the Galvantula and Joltik came out to take back their home.
The soundtrack title theme used when the swarms of Galvantula and Joltik surround Team Rocket is the same as that used in the opening of Arceus and the Jewel of Life.