You may recall the news that Pikachu was originally inspired by a squirrel. Well, a Yomiuri interview with Pokemon designers and illustrators revealed even more about Pikachu’s origins. For example, Pikachu has a lost evolution. Once Pikachu evolved to Raichu, the plan was for Raichu to evolve into Gorochu. Gorochu was planned to have fangs and a pair of horns. Because of balancing issues, this evolution was removed. Pikachu’s first prototype design was “daifuku-like creature in the shape of a long daifuku with ears sticking out”. It was during this design that the name “Pikachu” was born.
After the name “Pikachu” was born, Koji Nishimo says that it “really resonated for me personally and I thought ‘cute,’ and from there I started liking Pikachu more and more. For this reason, when I was shown the daifuku-like design, I asked Nishida-san “to make (the design) even cuter”. During its daifuku phase, Pikachu didn’t have cheek pouches. These were added when the team decided to make Pikachu cuter. The dark ear tips are one of the few remnants of the daifuku design. Pikachu’s back stripes were added because Nishida felt that, since you see the backs of Pokemon when they go into battle, “its back was lonely without anything on it”.
Pikachu’s design evolution wasn’t just influenced by a cuter route. When Pokemon Red and Blue was being developed, none of the Pokemon, including Pikachu, had any colors. When the Super Game Boy came out, it allowed Game Boy games to get colors. Ken Sugimori also said that “they say yellow is the color attribute of electricity”. This is how Pikachu became yellow. Pikachu was already very popular in the company, even as the number of Pokemon came together, something that became a lot clearer when Sugimori “printed out the pixel-art and had a popularity contest in the company asking ‘which one do you like? And Pikachu was by far the most popular
As for the anime, it was director Kunihiko Yuyama that decided that Pikachu should be Ash’s partner. Sugimori said that “in the game you choose one of Squirtle, Charmander, and Bulbasaur, but if Satoshi chose one of those three as his partner (in the anime) it would’ve created a gap with the kids who didn’t pick that Pokémon, so I believe that’s why he went with Pikachu”. Another reason, according to Sugimori, was simply because Pikachu was popular. The anime would be the final piece of the puzzle that gave Pikachu the design we know today. Sugimori said that “At first its body type was more plump, but its neck was made more defined and its back was made longer. From there the design on the game production side also changed. And that’s how we got the Pikachu you know today. By the way, I never expected to hear it cry “Pikachu!” in the anime”.