mmhhh... here some tips:
-You must work at 30 fps, or your animation results choppy (Try do to some practice)
-Improve the movement, especially the when they falling or punching!
-You need to have a VCAM, for having a best framing without moving all things that are on the stage (Remember to press the shift button, if you resize your stuff)
-The enemy reaction must improved, and the engieneers must be courage
-Try to learn how to draw (Background, Charachters etc. etc.) for the weapons, enemies and bloods it's ok if you use the original krinkels stuff, but if you want make the protagonist plz, don't ripped and do a recolored stuff from original. Oh and try to make your own background!
-The rest has already said andyyyy, so also follow his advice becouse his right
I do not know how many years of experience have made, the only thing I want to say is that all the animators have its own beginnings, aand i hope my review helped you