Please, no. That Eggman is just appalling. Even if, by some miracle, you could shade it well, it would completely clash with the style of the existing SRB2 sprites.
At least just study the way the best WADs have been made. I've said it before: when making a WAD, DON'T TRUST YOUR INSTINCTS! It takes a lot of hard work and a lot of practice to make something good.