Needs work
Graphics: The usage of Sprites already means that, in general, the amount of effort required to make the movie is decreased, but that is usually surpassed with good or superb animation. The problem here is that the sprites used were uncreative as they were merely edits of Sonic and Shadow sprites from the Advance series and highly uncreative.
Sound: The sound was nicely picked, but it didn't feel in-synch with the fight, try the Audio Portal there are plenty of good loops for fight scenes there. The sound effects were well chosen and well-used however.
Animation: The animation was "decent" at best, there were many problems here. The sprites looked awkward and low quality in such a large size and the background looked strange and didn't fit the characters at all. The text was significantly ill-used, with letters, despite clearly readable, occupying large amounts of space and the text itself getting in between the action.
The fight scenes themselves felt rather sluggish and had some difficulty in "flowing", more SFX would have spiced it up as well.
However, for a "junior" flash artist this isn't bad, it's actually a pretty decent initial work, you have a loading screen and proper "camera" movements and the animation isn't dis-jointed and wrong.
Conclusion: It's not a good work, but it shows off some minor potential. If you were to improve the storyline, further customize the characters and get better and more fitting backgrounds, that would greatly improve graphics.
The audio portal could serve as a fantastic way to get sound files and loops, and the fight scenes will improve greatly with added special effects and increased speed.
You might also want to re-consider the storyline, for it is over-used and becoming a huge cliché, creating a more "original" one would be in your best interest.