The Pikachu that has lost its ability to generate electricity is called Peakychu in Pokémon Pokopia. Peakychu is one of the special Pokémon Ditto encounters while restoring habitats.
Pikachu is normally associated with electrical power, so Peakychu's condition gives the character an unusual story problem. The loss of electricity distinguishes this Pikachu from the standard portrayal of the species and fits Pokopia's broader theme of Pokémon adapting to a damaged world.
Peakychu is one of several named characters with altered circumstances or special talents. Other examples include Smearguru, a particularly gifted Smeargle painter; Mosslax, a Snorlax covered in moss after sleeping for a very long time; and DJ Rotom, a Rotom possessing a stereo system.
The name is easy to confuse with ordinary Pikachu because it retains the familiar species name. However, Peakychu is the specific nickname used by the game for this electricity-losing character, not a new Pokémon species or an evolution.