That's the animation's fault. The background color that was turned transparent was the same color as the white (actually transparency) on the foot.
I think you could make the legs go further with each step. Also, I think that the hat could be a little shorter.
I'm going to take a break from my wario and waluigi rpg for a while due to the fact that I don't think I know what I'm doing. I think it would be best for me to actually learn the basics instead of rushing in with next to no experience, I just don't think I'm ready yet.
I will be working on the wario and waluigi rpg again, but for now I'm going to try to get a little better at spriting.