1.Zaraki is like a monster but he have a brain too. He learns his opponents movement and ability. That explain why he can win his opponents with just a rotten sharp sword.
2.Zaraki isn't join Gote13 because he want to fight, He told Ichigo to go home and he will manage all the rest in that condition. I think that can prove Zaraki isn't join Gote13 for fight only however he just fun with it.
3.Zaraki has a huge or unlimited HP power then he can fight untill he win.
1.Iba had save the Bleach.
2.Ikkaku has a little HP power in the first place then he can easily lose.
1.Yammi will be the one who will survive.
2.The number of faccion can't use for ranking espada. Uquiora is number 4 but he doesn't have one.
3.In my openion Stark is number 1 because he can steal Orihime from Zaraki and Ichigo so easily.