Needs more work
The overall feeling I had when the flash ended up was that you could have spent more time on it, maybe making it shorter in order to focus on the details.
The animation wasn't horrible and decent for a beginner at flash, I couldn't do better myself. Though work on the smoothness of it, try to make fluid since those lines moving were quite rough. I noticed the movements were really fast and the scenes really short, I advise you to make the actions slower and the scenes longer, it will be less painful for our eyes ;).
I didn't like the drawings to be honest, they were to childish for my taste. Spend more time on the details of the drawing, especially for the backgrounds of the scenes, try to use thinner lines also. Though I keep in mind you are twelve and that you do a better job than what I could do, so I can't criticise to much.
I tried to find any plot in your flash but I didn't find any, it was just a fight and we don't know why these guys are fighting, I just recognized some famous characters but it doesn't really count as a proper plot. As for the audio, you did a good choice and the sound quality was quite close from the original track, so good job.
Overall, keep practising, you are on the right way.
*Review Request Club*