Pokémon Model Ripping Project

[The 100 Mega Shock!]

Well, the game makes the cel-shader work using all of the textures at once. If you just applied the main texture with a simple cel-shaded material, you'd get "double shadows" where there's painted-on dark areas in the texture, so Game Freak designed the shader to take additonal maps that stops that from happening and give them more control over what areas are lit and shaded, and more importantly what color the shaded areas are.