You probably got his frags from a Lucky Stars. Either one works as one of 6 paths weaknesses comes from being blitzed round 1. Kisame fusion mode is a better choice as you can retain your shields and buffs as well as his high repulse chance and life regeneration from his passive. Madara 5 kage isnt a bad choice either. But if you have to chose between the two, I'd go for kisame as you have more fragments of him.

Yup, though it would be better to run king of hell, gamariki than gamaken