Amazing potential.
Nicely coded. This looks really it could really be great finished. There's just a few things you can improve on: First and Foremost: a preloader. I'm assuming you just forgot that. Not a big problem, but it did get a little glitchy when I tried to play before it was ready. Second: I like the way you included a 2-player control, but it came at the expense of the ease of the controls. It's too confusing to properly work your character. Third, and this is more of a personal thing, you need more characters. At the very least you need to add Ness, Pikachu, Fox, and Donkey Kong. Also, a scene selection wouldn't hurt. I'm not trying to ask to much of you, these are just a few suggestions. Just one more thing (I promise). If I were you, I wouldn't be afraid to ask some other people for help. Between all of the countless users on Newgrounds, I'm sure you can find someone(s) to help you code anything you need help with.