So it's Hashirama, Tobirama, Tsunade, Naruto & Nagato vs Madara, Izuna, Obito, Sasuke and Itachi.
Quite the interesting match up. Madara and Hashirama alone can alter battlefields and landscapes. I wonder what this battle could do. However, this is besides the point. I see the OP designed this with the intent of each character fighting one on one with another in the order presented with the exception of Obito and Tsunade. However, this will not be the case as Team Uchiha possess some of the most intelligent characters in the series. Team 1 has intellectually powerful characters but not as much as Team 2.
Following the play-style of each character, Naruto will use Kage Bunshin and rush in with a standard Rasengan and clash with Sasuke's Chidori. Both fall back and decide to use their "trump cards". Them being Biju Modo and Eien no Mangekyo. Seeing that Naruto has went into Biju Modo, Obito will charge in with his Edo Jins while staying back with Madara and Itachi. I presume that Madara does not possess the Kurama.
The rest will not stand mute. Hashirama will use Flower World in which Obito responds with the Seven Tails using a Bijudama and blowing up and causing the first devastating explosion. Sasuke will stay in his Susano'o, Obito will go Intangible, Madara and Itachi will do the same as Sasuke.
Nagato with Tobirama will walk into the arena with Fully Charged Kyubi Cloaks and Itachi along with Sasuke confront the duo. Tobirama's only known jutsu was Hirashin and following the no assumption, he will be beaten in no time with Amaterasu spam and Katsughi. The Itachi and Nagato will confront one another but hold back. Itachi will by instinct protect Sasuke from Tobirama if needed.
The first major battle would be Nagato vs Sasuke and Itachi which will be pivotal to the battle's outcome. The two will clash and clash and clash but both will fight for a small advantage over the other. We can tell from Nagato's Change of Heart that he was unsure about his "dream". This will lead to his defeat as Sasuke and Itachi will masterfully use Izanami on the Rinnegan holder and win that fight.
This leaves Tsunade, Hashirama and Naruto on Team 1 an Team Uchiha still intact. However, soon enough Itachi will fall to his stamina issues and due to losing an eye. Hashirama would've been clashing with Madara, both not going all out yet. However with the loss of his brothers death and losing Nagato, Hashirama will go into Sennin Modo combined with Kyubi Chakra. This will create an "Infinite Sennin Modo" effect.
Madara stabilizes his Susano'o to a near perfect form. Obito seeing that the Edo Jins will be needed to defeat the Chakra Monster Trio decides to split the the fronts. The Two Tails and an exhausted Sasuke fight Tsunade. Tsunade will do all that she can but will in the end lose but not without partially taking down Sasuke. The Young Uchiha is no longer able to fight and Tsunade is alive but unable to fight. She summons Katsuya to heal herself which the Two Tails with fail will try and destroy.
Obito with the Third through Seven Tails along with Madara confront Hashirama and Naruto. Naruto will run in and fight Obito in a one vs one and instantly go all out with Kurama guiding his attacks. Obito will not be damaged one bit but will not be able to defeat Naruto. Hashirama fight Madara in Sennin Modo with his various Mokuton Techniques which Madara will obviously counter with experience.
Obito will not warp Naruto's Kage Bunshin due to not having the pressure of Kakashi, Gai and Kirabi present. It will be a clash with Naruto trying to make Obito go tangible and defeat him there and Obito trying to warp Naruto or kill him here. Naruto obviously couldn't do what he hoped for and Obito couldn't warp him. Obito will confront him close up and use Mokuton to absorb a significant amount of Kyubi Chakra.
Hashirama seeing that he needs to go with his trump card, summons Shinsusenju and with high difficulty, defeats Madara. Obito then eventually in a long dragged out battle defeats Naruto with a clean kill when the Kurama Chakra is temporarily out.
Hashirama and a healing Tsunade are left on Team Senju and Obito left on Team Uchiha. Hashirama with his various fuinjutsu will defeat the Edo Jins and Tsunade will be healed. She will not be in her prime state that she started in but will be able to battle. Obito will fight head on with Hashirama and Tsunade. He will warp Tsunade but will be unable to defeat Hashirama. With Hashirama going for a kill, Obito as a last resort uses Rinne Tensei to revive Madara, Sasuke and Itachi.
With the overwhelming power of the trio, in his prime Hashirama could defeat them but due to exhaustion, so-cums to a loss. Team Uchiha Wins.
