[FS]

I wouldn't try selling a game made with someone else's program, nor with a copyrighted character like Megaman, unless by "scratch" you meant you want entirely new characters. Assuming that you'd look up a bit of public interest for 'your' game, that'd be a great way of attracting the attention of hungry company lawyers.

I'd suggest you just use existing characters and release the game freely online. You can easily find complete spritesheets of many popular game characters. Or start ripping sprites yourself, and build your way to editing/making your own sprites.