Hi jeiki
I'm not of fan of the selout to black, if you're going to do that at least add intermediary shades between the black and the darkest color you have now. Not to mention the way you've done it now seems rather random. But my preference would be if you just went with black outlines or not.
The lineart in both could use some cleaning up, there are a lot of jaggies. Is that yellow guy carrying a shield? It looks like a yellow fleshy blob. Either make it a different color or make it more metallic by introducing higher contrast and hue shifts. Looking around for metal references would help there.
The feet on both could use a lot of work. Right now they're undefined blobs of flesh. Also, both of the feet art pointing in the same direction, but their poses would suggest otherwise. The yellow guys feet are different sizes, too.
In fact, the line art on both could use a lot of work. They're both rather weak and it doesn't seem like you spent a lot of time on them before you rushed into coloring. The yellow guy has a weird indent thing going on with his jaw, and I'm not sure what that mohawk is supposed to be.
I don't like the amount of internal black lines, either. Like with the guy on the right: most of his colors are different enough that they don't need black lines to indicate seperation.