>>44484185Those are Starters, which you're conditioned to hold bias towards from the moment you get the game, if not earlier. Not only that, as mascots, they're either too basic on paper, or don't get the point across well enough that they end up taking more time to understand.
Pikachu works because its design elements embody the fundamentals of a "Pocket Monster", with its concept of "cartoon electric mouse" being one that can be universally understood no matter who you are or where you're from. It also helps that Pikachu had an initial allure to it back in Pokemon's infancy stages in Japan, due to it being a fairly rare Pokemon in Viridian Forest, and not only that, a Pokemon with a typing you otherwise quite literally were not ever going to get to use until the halfway mark of the game, since the rest of the Electric Types Kanto had to offer were either in the Power Plant or Jolteon.
