GUYS youre forgetting, that we talk of ALLMIGHTY KYUUBI
Really, what ksuubi did in his tailedbeastmodewith only six tails was close to being god.
No uchiha has a power close to chibaku tensei and even that was not working on nearly full powered kyuubi. He could just finish them of with his chakra arms, throw mountains on their heads or blast them away with a tailed beastbomb, from a distance, the uchiha can barely see him.
Hes fast like *I dont know* I dont see any sharingan avoiding his punshes. One hit and the XY Ninja will never be reborn again.
Susanoo? just crush the whole ground all over the battlefield. Kyuubi can throw susanno and its user from one hand to the other.
He just has to be careful because of totsuka, but since naruto could maybe even use Sagemode at the same time, he can avoid any attack.
The only unknown factor is madara.
Kyuubi/Naruto would wipe out the Uchihaclan in a few minutes, maybe just seconds. (be realistic nobody can take on direct hits like Tendo)(I dont think the standard Uchiha is fast enough to avoid this attcks.
Than, there would be just madara, Itachi and Sasuke left, cause they can protect themselves with susanoo for a short time.
Rinnegantechs like allmighty push dont work on Kyuubinaruto, so that defence is down. Susanoo cant deal with attacks from those chakraarms, if they come from all sides. (I guess naruto could even make Kyuubi/narutoclones)
Itachi cant keep up susanno for long and even if he can, the powers that would smash susanoo all over the battlefield would be very dangerous for the user, if he keeps standing in its center.
Since they all know (I guess Itachi is clever enough) Genjutsus wont work on Perfect Jinchuriki. I doubt, that they try to use them, even if they do, Naruto in his tailedbeastmode cant be hurt (Oros iddontknowthename sword failed).
Madara could create meteors, but that would just kill himself and very other person around. Maybe kyuubinruto would even survive tht, since being cought in solid stone didnt really crared kyuubi.
The only way, to stop a perfect Narutokyuubiduo is to make a perfect Juubi/Ninjacombo. Or you must hit naruto, before he goes to this version two state.
A battleprepared Kyuubi/Naruto. No way.
Too strong, too fast, too invulnerable, too large range, too fast attacks, too much stamina
(Since even the painfight didnt seem to exhaust kyuubi) And what pain did to kyuubi was more, than anybody could survive.
I know, that you say, im overhyping, but kyuubi has bin the only instance in the whole manga, that never showed weakness in a real battle.
(sealing him was just possible, because the fullformkyuubi is that big and it seems he moves in slowmo compared to th vers.II tailedbeastmode.)