Bowser complete!

Try looking at his sprites from Mario & Luigi Superstar Saga if you need more references for other angles
upon closer examination, I do have a suggestion for your side facing sprites - try moving his horns up closer to his eyes, and make sure his hair goes past them a bit. That should reduce the "ninja turtle" appearance a bit
edit - took a moment to actually photoshop what I was trying to suggest, check it out here - https://www.ff6hacking.com/misc/imgshk.png/