Needs a lot better sound work
Your graphics and animation overall were pretty nice, even for a sprite flick. However, your sound effects and choice of music were, I felt, poorly implemented. It was extremely distracting listening to background music that I recognized out of context from movies. I'm more impressed by original work, and while your animation was certainly a class act, I felt your music selection was less than that.
I want music that goes along with YOUR animation, not music which goes with an entirely different movie which you happened to like. It's good music in its own context; it just doesn't fit with your flash.
As for sound effects, I felt they were poorly implemented in the sense that they seemed forced and often out of synch. When the Megamen were shooting, it felt like there should have been more than a wimpy "zing" to accompany a charged, devastating bolt of plasma. If you're going to use sound effects, they can and will make or break your presentation.