So far I've put myself forward to control Renji, that's it I think we still need Rangiku and the two opponents. 

Yosh - Actually you can be Captain-level but thankfully we have a number of good people who like to cap themselves which is a breath of fresh air I must say! So you can choose. As long as you don't go God-mode or have a silly ability you can be anywhere from I would say Lieutenant level (to be relevant) to strong Captain level.

[B]Edit:[/B] Wow. In fact Fox was the only one who had developed or at least had explained his Bankai, everyone else (Including myself) Hasn't written out a Bankai, although I will say I definitely have one and a couple others are just 'not yet revealed'