The Pikachu that lost its ability to generate electricity is nicknamed Peakychu in Pokémon Pokopia.
Peakychu is one of the special Pokémon Ditto encounters while restoring the game’s habitats. The character’s unusual situation gives Pikachu a story distinct from its familiar image as an electrically powered Pokémon.
Pikachu normally produces electricity through its cheek pouches, a defining feature in the Pokémon world. Pokopia instead uses the loss of that ability as a character detail, showing that the game’s Pokémon can have personal circumstances and problems that are not simply battle statistics.
The name Peakychu is easy to confuse with Pikachu because it is a playful variation of the species name. It is not a new species or an evolution. It is the special nickname used for this particular Pikachu in Pokémon Pokopia.