"The Shinobi Unite" (忍達の共演, Shinobitachi no Kyōen) is episode 449 of the Naruto: Shippūden anime.
The Konoha 11 are summoned by Tsunade. She and Jiraiya inform them that Sasuke has killed Orochimaru, and has been working with Akatsuki. They provide the Konoha 11 with intel on Sasuke and Akatsuki, hoping to bring Sasuke back to Konoha before other villages deal with him for aiding Akatsuki. Sasori presents Akatsuki with his army of human puppets. Sasori and Sasuke discuss what is to be done with Konoha. Kiba catches Sasuke's scent, and follows it with Naruto and Sasuke, who come across Sasori, Deidara, Hidan, Kakuzu, and Zetsu. Itachi reveals himself to Sasuke, having faked his death, and questions his intentions before leaving. Kiba, Naruto, and Sasuke are joined by the rest of the Konoha 11. Team Asuma fights Hidan, Team Guy fights Kakuzu. Sasuke arrives, having betrayed Akatsuki, and deactivates Deidara's landmines. Team Kurenai fights Deidara while Zetsu retreats. Naruto, Sasuke, and Sakura destroy Hiruko, revealing Sasori, who summons several reincarnated puppeteers, each of them wielding more human puppets. Shinobi from the Five Great Shinobi Countries arrive and engage the puppets, leaving Sasori for Team Kakashi. Sakura manages to destroy Sasori's Third Kazekage puppet, so Sasori reveals his human puppets made from the Third Tsuchikage, Fourth Raikage, and Fifth Mizukage. Team Kakashi uses the Summoning Technique, but Sasori uses the Third Tsuchikage's Dust Release to instantly take out Aoda. Jiraiya arrives with Konan and Nagato. Sasori attacks Sasuke with the Mizukage's Lava Release, but he is protected by Itachi's Susanoo. Itachi berates Sasuke for wanting to fight alone, and Sasuke activates his own Susanoo. Sasori attacks the others on Gamakichi with Dust Release, but Nagato absorbs the attack. Konan holds the puppet in place, allowing Naruto to destroy it. Sasuke destroys the Raikage and Mizukage puppets with Susanoo. Sasori reveals his true puppet self, and brings out more human puppets. Naruto and Sasuke destroy Sasori and his puppets with Rasenshuriken and Kagutsuchi. Sasuke agrees to return to Konoha, but denies being comrades with the others again, intent on changing how the village works.