>>51373753The real reason? Competing design philosophies. Every Pokemon is created by one of several artists, each with their own aesthetic tastes. Kanto leaned heavily into the "Monster" and "bug catching" aspects of Pokemon, which is why the majority of Kanto Pokemon are simplistic and more natural looking.
Take, for example, Fire type starters. The first two look more simplistic, with few extraneous markings and flourishes. The first three have 3 colors as part of their color palette, while everything from Gen 4 onwards increases the amount of colors. Pokemon's design philosophy has shifted so much that it's evolved much like Araki's artstyle has evolved over the 35 year long lifespan of JJBA.
