Although I don't think the fight will start until chapter 400, I thought I would put my own prediction here since there was speculation about the fight earlier. Since they are fighting in such close quarters (unless another area to battle pops up), I have a feeling that there will be a couple bigger group battles…..
Luffy vs. Lucci: Luffy goes Gear 2, and is able to keep up with Lucci until he goes into Leapord mode. Luffy is knocked out/thrown into the pit/incapacitated for the time being....
Zoro + Ussop vs. Kaku + Fukurou: You get the longnose matchup and Zoro gets his revenge. Zoro and Ussop win the fight, Zoro joins up in the other group fight while Ussop goes to free Robin, and help out Franky
Sanji + Nami + Chopper vs. Jyabura + Calipha + Kumadori: The rest of the fighters join in the third group fight. Chopper and Nami have been fighting together alot in this arc (Iceburg mansion, trying to go to the top of the courthouse), and Sanji will most likely stay with Nami and try to protect her. Fukurou and Kumadori are defeated, and then Lucci and Zoro join in the battle. The Lucci + Jyabura matchup reminds me alot of Zoro + Sanji in the Davy Back Fight. Zoro, Chopper, and Nami are defeated.
Ussop + Robin + Franky vs. Spandam + any Marines left: Ussop makes it to the top of Justice tower, to find Spandam backed up by any of the Marines left in the tower. Ussop uses a flash dial, and is able to get some cola to Franky (I'm guessing Ussop grabbed some cola on the sea train). Franky, now powered up, takes out the rest of the marines and messes up the other half of Spandam's face, while Ussop frees Robin. Franky goes to help Sanji, Robin goes to revive/retrieve Luffy, and Ussop snipes from Justice tower to help give the Strawhats the advantage in the fight.
Sanji + Franky vs. Lucci + Jyabura: The combined strength of Franky and Sanji finally take out Jyabura, but they cannot defeat Lucci, even with Ussop's support. Both Franky and Sanji are defeated. Lucci jumps up to Justice tower, and instead of running away, Ussop stands up to Lucci and is able to hold his own for a little bit. Unfortunately, Lucci gets a punch in, destroying the mask, and is about to give Ussop a deathblow....
Robin + Luffy: Robin finally finds Luffy and revives/retrieves him. She points out that Lucci is up at the top of Justice Tower, and that Ussop is in trouble. Luffy Gomu Gomu Rocket's up to the tower just in time to save Ussop...
Luffy vs. Lucci: The final battle, and Luffy, with all his nakama depending on him, finally is able to defeat Lucci. Just as Lucci recieves his finishing punch, Spandam regains consciousness, and presses the button. Buster Call Time!
This way kind of answers all the concerns people have said in this thread. Ussop is able to gain the confidence he needs (fighting Kaku, taking on the marines, sniping for a bit, and even taking on Lucci). Zoro gets a strong opponent, maybe can improve his skills a little bit, but will not really have that much of the fight focusing on him. Sanji gets a long time to shine in this fight. Franky gets to fight as well. And like Nami in Arlong Park, I don't see Robin fighting in this arc.