Not bad!
Just let me start by saying, I like this. So, before I go on, just keep that in mind.
Now, graphics. They were fine, some of the sprites coulda used a bit of tweaking. IE reactions to being shot with a heat ray or being hit by an icicle. But that's not terribly crucial.
My biggest problem was with the framerate. Too choppy. Ruined the spirit of the whole flash for me. But, hey, whatever works. ANd, like you said, you made it when you were bored so one can't expect top-notch work under those conditions. Just enough to the point at which the author gets...unbored.
Style works nicely, quite creative. Use of sounds and graphics came together well, and it was tasteful. Nothing more said.
I could recognize all of the sounds, and that was fun. I like the one from Ice Climbers. Top notch.
The fighting was well-played, sufffered from a poor framerate, but still.
Overall, I liked it, and I'm mostly curious as to what that awesome Title font was. That looked stunning.