Oh, lord...
Um, OK, first of all, use a reference for the characters so that you can draw them better. Pull up a picture of Bowser and try to draw him from the reference, because your drawing of Bowser was pretty bad; you used the oval tool and line tool to many times, and you just scribbled on the hair. You didn't draw Mario and Luigi to bad, plus, I found it funny that Luigi just fell out of the sky at random and didn't do anything in the fight. The voices were kind of cheap, and, well, the backgrounds were not too good. I give this a 3 overall.