Pretty good for a 3rd flash !
Also, it's pretty amazing this is only 306 kb :O
You should crank up the quality a little though, and add some sound fx (like when he jumps onto a goomba, for the explosion, megaman shooting, etc.)
But again, it's pretty good for a third submission.
Just make it longer, and add some sounds, and spruce up the quality, and you should end up with quite a nice flash.
Good luck on your future flash !