Pikachu is the most recognizable Pokémon, largely because he is Ash Ketchum’s partner in the anime series. He is the official mascot of the franchise and is considered a special companion to many Pokémon players because he was chosen by Ash instead of the other three starters. That makes Pikachu unique, which generally appeals to audiences. Pikachu was made specifically to be popular. His yellow coloring and neutral look appeal to all genders. Primary colors are recognizable from a distance, and the creature's large eyes, mouth, squashed face, and ears are features commonly seen in cartoon characters and babies (minus the ears). Characters with child-like features have a worldwide “cute” appeal.  Clefairy was originally going to be the mascot, but they chose Pikachu instead since Clefairy is pink and too feminine. The Pokémon company feared that Clefairy wouldn’t be interesting to boys, which was the prime videogame demographic at the time. For all of these reasons, Pikachu became popular and is a safe bet to put on merch. Most consumers won’t buy other Pokémon unless they’re a personal favorite.