I’m not sure about Donkey Kong but I know that Pokémon Red and Blue played on the GBC just get shades of the colors each city and town is named for such as Pewter being greyscale while Cinnabar gets a reddish tint on the overworld map. Yellow uses more color for the title screen, Pikachu interaction windows, and the Surfing Pikachu Mini game. Yellow also has more vivid colors for each town and city that matches their names and the water and grass stand out more.