You're learning. The animation is getting a bit smoother and your fight scene was much better this time. Your sprites don't look great; are you exporting at 100% image quality in your publish settings? You can also increase your sound quality the same way (the default setting for both is 80% i believe).
Anyway, this is much better than your first. The fight was more balanced and exciting. I would add some more special fx in your next flash. When an object lands, try animating a small dust cloud. When Megaman shoots, add 1 or 2 frames of flash on his armor. When Bowser's fireball crashes into something, try adding some smoke effects. Some of your sound fx were off too; they sounded like you were using your mouth and a cheap mic. There are great sound fx websites out there. Flashkit.com is a good start. If you want to go for consistency, try only using Mario and Megaman sound fx, filling in with other generic sounds only when you don't have another option.
I hope this info helps. Don't take it too hard, as you've made a lot of progress already. Looking forward to your next one :)