The grandparent's comment is "relevant" because a pikachu is an Electric-type Pokemon. It can attract/store large quantities of electrons, and also repel/release large quantities of electrons.

While pikachus do eat other food, fruits/Poke-food/etc, it is unclear if they need a source of electrons to sustain themselves. They may just pull the needed electrons out of the their surroundings. However, I seem to recall an episode where Pikachu was sick due to a prolonged lack of access to a large current source.

[1] http://bulbapedia.bulbagarden.net/wiki/Pikachu_(Pok%C3%A9mon...