Hey Blue Emerald, out of boredom, I've tweaked up your badnik sprite... Even though I didn't know it was supossed to be a slug (I assumed it was some sort of caterpillar, like in the original games), so well.... I only realized that after I had made this.
Use it if you like, anyway:
I have one big suggestion for your future works, though. The colors you choose didn't have enough contrast between them, so they're pretty much unnoticiable. Try using more contrasts on the colours if you want to make shadows and highlights.