Eh...
I'd recommend practicing a little more next time cause this wasn't very good.
Ill tell you some of the reason why I think that.
1. Use onion skin. I know that you aren't because your FBF isn't nice. FBF has to go smoothly to look good, one frame should at least look a bit like the next.
2. Have a background. A background can do a lot for an animation. A plane white background made me lose interest the moment i saw it.
3. Make it pretty. The "magic" consisted of just for example a purple ball with white lines it it. Add some glow, blurred lines, anything as long as you make it pretty.
4. Keep the proportions right. One moment the black stick had normal length arms then all of a sudden when he blocked an attack he had these abnormal rubber arms that were bigger then the ones before.
5. Make boundaries. I hate it when people use the edge of the animation as a wall. And you didn't even have any ground!
6. Make your own style. I wouldn't advise you to use a style like for example DBZ. Make up your own super modes and spells and stuff.
7. Clean it up. I saw random dots and lines several times and it doesn't look good. You should erase anything that doesn't look right. And use layers cause some times it looks like you didn't. And if your making the entire screen a specific color, make sure you fill the entire screen.
Well anyways you should keep practicing on stick figures, its good practice for certain moves and such. But you should look through you animation and see if your satisfied, or better yet, have someone else look through it before you submit it to Newground or any other site. Use more effects though, like shaking the entire screen and glow and such. If you don't know what anything I just said to you is, check out some tutorials on the web. There are tons of em, stretching out over almost everything. Well good luck on your future animating career. :)