Minvoltius is a Fossil Pokémon of the Stellé region, and is Rock/Electric, known as the Protomouse Pokémon. Its ability is Volt Absorb (Hidden: Galvanize.)
LIBERTY Dex: It was the ancestor to such species as Pikachu. Despite its resemblance to Plusle and Minun, its closest living relative is Dedenne.
JUSTICE Dex: This Electric-type Pokémon thrived millions of years ago. There have been unconfirmed sightings of it in the present day.
Notes about Minvoltius and Stellé Form Audino
Many would consider Minvoltius to be the Pikaclone, as it is the one that is a true "new" mon and not a regional variant. However, in Minvoltius' time, there was neither Pikachu nor humans to classify the similarity of species. Hence, Minvoltius cannot be the Pikaclone.
Stellé Form Audino, however, adapted to its environment after Pikachu became a separate species. It also has the Electric typing, the cute and cuddly build, and electric cheeks. In the real world, we still call the red panda a panda due to its "wrist thumb" even though it is only a very distant relative of the giant panda; so it would not be a stretch to call Stellé Form Audino the Pikaclone of the region.