Not bad, but could be better
Right, you've come up with a decent enough game that has some pretty good looking moves and special moves. What I would suggest to make it a better game is to give us some AI to fight against. Most people these days sit behind one computer screen, rather than all crowding around one screen to play multi-player on a single machine.
Yes, you've identified the need for the return to menu button (There are buttons tutorials on NG, if you're stuck). Why not make that into a menu mouse over tab, where it expands if you bring the mouse over the top, so you can minimise what is taken from the gameplay area? More options are usually better in games such as this and while you'll be working on things like additional backgrounds and possibly even a plot for these games, you're going to need to change some of the basics, to increase the game's appeal.
In the game itself, perhaps have the numbers reduced to background (i.e. don't show them to the paying punters) and just have graphics there, instead. With the weapons, perhaps have them take off more than just half a hit point per hit, otherwise it will be a long and boring fight. The critical hits will do more, as will the special weapon, so factor these in proportionally. With the advent of the AI, you can make it best of three, so it becomes a proper challenge.
There is a basic frame here, that probably does require more programming assistance. With that help from the Flash Forum, you'll be able to get a more appealing finished product and from there, you can produce a better finished piece. I look forward to seeing when it's done.
[Review Request Club]