Amaterasu proved himself a Badass for the ages when he opened all Eight Chakra Gates and obliterated the Kyuubi of that world - and surviving the use of such a Dangerous Forbidden Technique. The sheer force of the attack took the Land of Waves with it.
Kazama gets his moment when he vaporizes Orochimaru with his new Storm Flail technique while Orochimaru was in his true form and when a piece of him survives and tries to take over Kazama's body, Kazama stops him and finishes him off with an EPIC "The Reason You Suck" Speech that completely deconstructs him and destroys his soul!
Mikoto saving Yugito and Mei from Amatsu-Mikaboshi and then stalling it.
Minato killing a boss summon with a single Rasenshuriken.
The Sage of the Six Paths PERIOD. He effortlessly destroys both Izanagi and Hashirama, after being resurrected at the very moment of his death.
The entire final battle against Susanoo. Especially the ending, where Kazama summons all of the friends and allies that he has made across the multiverse to aid him in defeating Susanoo's Edo Tensei Army, and in essence, delivers one massive Shut Up, Hannibal! to the ancient Uchiha.
Here are some more specific ones during the fights.
Good Orochimaru and Manda being Big Damn Heroes saving Haku and Mei from the Second Mizukage.
The Dark Wolf curbstomping the Third Raikage. The fight would have been over within a minute if he wasn't a zombie.
Kuebiko getting his act back together after holding the Idiot Ball in the Dystopia arc and curbstomping Mu.
The Sage of the Six Paths proves just how powerful he is by taking on Izanagi and Hashirama. With the Rinnegan and Sharingan. At the same time. And he didn't even have to try to beat them into the ground.
Izanami burning Izanagi's eyes out then effortlessly shutting down his 'perfect' Edo Tensei.
The fight against Teikoku!Deidara and his allies. The Arashi managed to take out a guy who described himself as a walking volcano, and who qualified as such due to being a psuedo-jinchuuriki of the Yonbi, and his minions: a Sound!Naruto as fast as Minato with the Cursed Seal, and a Naruto who had stolen many of Konoha's clans ninjutsu who had modeled himself after the Joker.
The Dark Wolf, Konan, Yugito, and Teikoku's Mei managed to take on Pain/Nagato, after he had sealed all the biju save the Kyuubi inside him, and later turned into something resembling an Eldritch Abomination.
Teikoku's Orochimaru and Kabuto get one when they beat Karasu, Chibaku, and Haku offscreen. Later, they, along with Teikoku's Kushina and Mifune, mopped the floor with them, Inari, Izanami, Yugito, and Kitsune without even breaking a sweat.
The Red Zetsu managed to fight and defeat the Dark Wolf with his Corrupted Sage Mode, after sending his legions after her, Naruko, Sasuke, and Konan for days on end. If it wasn't for Tobi showing up to save them, he would have killed them all.
Say whatyouwillabouthim, but the Warlord has apparently had many of these offscreen. He was apparently able to force a deity to retreat/destroy its anchor to the world alone, something the Arashi Clan had to struggle to do once, and was unable to do another time, as well as take on Kaguya Ootsutsuki and manage to scrape out a win, albeit by distraction, and has made his chakra chains strong enough that it would take a Kyuubi to break them, and though we have yet to see him in battle, it is agreed all of Teikoku that he is by far the most powerful member. Considering that this is a group which includes a Mad BomberMagma Man, an Orochimaru with the Mangekyo Sharingan and Awesomeness by Analysis, the deeds of Teikoku Mei above, a Zetsu which managed to overrun an entire world with copies of himself and a Corrupt Sage Mode, among others... and this guy is at the top, stronger than any of them, despite the fact that he has no real friends, or even allies, and that everyone else hates him and would probably like to see him dead... This guy, even with the Sage of the Six Paths in the story, is high in the running for Multiverse's Strongest Man.