This piece and most of your others have a bunch of redundant colours. This one has only a few, but some of your others have over 100. Did you use translucent/partial-opacity tools while working? Did you scale them, or perhaps use gradients? Uncontrolled colours like that are generally not accepted to PJ.
No, i didn't use gradientes, opacity tools in my pixel arts. I usually to use many colors in my process. I'm still learn how to control this. Sorry if i broke some rule.