Here's my two cents.
I like this game. I like the art style, the levels, and the characters. I can tell you put some work into this and I commend you. I have only two problems with this. Number one would be that, as far as I could tell, there are no special moves. So many of the characters have weapons, but there's no special moves for them, which is irritating. Don't get me wrong, I know that just programming this game took effort so I'm not calling you lazy or anything (I tried once to make a fighting game in flash) but a couple special moves would have been nice. My second problem is, as someone already mentioned, the AI. The first time I fought Alucard I got him to about 1/3 life but he beat me. The second time I held up and forward and repeatedly tapped the kick button. Through some glitch in programming I began some sort of homing kick where even though I was holding up and right, Pico would turn around and come back at Alucard when I was on his right side with jumps that had very little horizontal movement. I continued to beat all characters with this horribly cheap tactic. You should have a few people you trust beta test it and try to find things like this so that you can implement something to punish it, or at least change the programming of your jump so that it doesn't conveniently shorten them to match the distance to the opponent. Oh, and though this isn't a major problem, you should have a few built-in combos for each character. Hope this was helpful.