At this point, I'd probably focus on what its movelist is going to be and how it plays. It's not fun when you're doing an original character (ie: not ripped from a game) and then discover that certain attacks just don't work at all in your system (ie: the Mario I'm sloooooowly working on).

Also you'll definitely want to sprite the required animations as shown in the docs because, well, they're required!

Also I'd recommend reducing the character's colors to something more manageable so that you can do palettes. It looks simple enough, but all that anti-aliasing jacks up the numbers really badly, so you'd need cleaner lines to work with.