How to improve this sheet?

[tent2]

I tried to upload this in Mega Man Custom/Edits but it was rejected.
Any ideas of how improving it to meet the standard qualities?

[Ton]

Aside from this being a recolor and a cut/paste jobs, the dark palette on Sniper Joe makes him unreadable.
Additionally, the pod he's in is a bit strange and there's nothing about it to indicate that it's come kind of Dr Robotnik flying pod or something. I think that's what it is, based on the sprites.
Some of the shapes are either stretched and blocky (Spike ball) or just oddly shaped (liquid ball animation).
Some of the sprites also have too many colors for NES.