I don't care how obscure he is, if you make a sequel to PASBR then you've absolutely got to have Kutaro from Puppeteer in there. Anyone's who's played Puppeteer knows what I'm talking about - he has got a move-set perfect for a game like this.
And I agree with the common sentiment to make it like Power Stone and have characters battle it out on a 3D plain. Power Stone is still my favourite fighting game anyway, so that design choice would be a dream come true.
And drop the super system. Just have big ass health bars like Power Stone.