What color scheme does the Spongebob character use?
There's a Photoshop trick to find an average color scheme.


Starting with an image, I chose one with the main BobSponge's characters.





From Photoshop apply a Pixelate filter, or choose an Online Pixelate Filter Maker like pinetools.com/pixelate-effect-image. With this you get a small color map from which to extract the most important or essential colors of an image.