not bad.
A little drawn out with the vanish fighting, but other than that it was a good fight. Surprised you didn't use super shadow. Most people just bust that out for no reason. I half expected him to turn super right at the last part.
A few things to improve. First, get a preloader. They take no effort to throw into the flash. just get a newgrounds one in the downloads section. It doesn't look good when it is just a looping movie. At least it wasn't one of those movies that doesn't have a clear end and the end and beginning blend together to the point it takes 4 times before you realize it's looping.
Second, some credits would be nice. I'm assuming you got those sprites and music from somewhere. I know you didn't make them. Credits are a must for the people who actually put effort into making sprites or ripping them. It's not as easy as you think.
That's about it. You got the style down, and it is an overused style, but since it was for a contest, well, it's probably supposed to be that way. Anyway, that's it. The fight was actually fantastic with the exception of the few times someone liked like they hit nothing and all of a sudden you see something flying. Just keep the stuff I mentioned in mind and you should do okay.