fat_pikachu
A Pikachu as depicted with its original, plumper proportions. Described by original designer Nishida Atsuko as "dumpling-shaped", with the defining trait being the lack of a clear separation point between the head and the rest of the body.
Gigantamax Pikachu is based on this version. Sometimes also depicted with a white (or darker yellow) belly and a tail similar to Raichu's - this design is based on its sprite from Pokémon Red & Green.