Alright, so me and a couple of my mates decided to make a mugen full game based around Mario, and possibly some guest characters. Right now, the roster consists of Mario, Luigi, Peach, Koopa, Yoshi and Red Koopa bro (modified by me) and we decided to let you decide what characters to add. We are, however working on a character for this game ourselves: Larry Koopa!
Also, if you want to suggest stages, we are open to that as well. We currently have five stages in the alpha version, which will be released soon.