I dunno if this has been discussed at yet, but I was wondering what your guys opinion of the other 3 admirals are, in terms of their powers. We haven't even seen Red Dog or Yellow Monkey, but we've seen Sengoku, and a frail man like that must have some amazing power, or they wouldn't have made him Supreme Admiral.
Here's my opinion:
I think Red Dog ate a Meru Meru no mi, like Ace, and can control fire. That would explain his name. He would have power over fire and be able to burn things. That way, he could counteract Kuzan if he ever got outta line for some reason.
OR… Perhaps he ate a yajuu yajuu no mi: Model Cerberus. That is, he can turn into a flaming dog that could beat the crap outta stuff. And perhaps he can do a seven-form transformation like Chopper.
I think Sengoku ate the Shindou shindou No Mi, which allows him to create massive earthquakes and control elemental Earth. This could easily make him the most powerful in the military, and even allow him to make himself invincible by turning himself into solid stone.
As For Yellow Monkey, I think he ate something similar to Eneru, which allows him to control lightning, but at a much higher level, in which he can actually become lightning. Or perhaps he ate an Oozaru Oozaru no Mi, Model: Spider Monkey, which allows him to attack very quickly. And like Red Dog, he could have mastered a 7 form transformation.
Personally, I also think Yellow Monkey is Luffy's Grandfather. When Kuzan said he "Dealt" with him long ago, this could mean the admirals never get together much, and his presence is a pain to behold... or something like that. That would explain why Luffy got nervous.
