Eien No Mangekyou Sharingan Sasuke can beat them all at the same time. You people do not understand the veracity and potency of his Amaterasu mastery, let alone his obvious unlocking of Perfect Susano'o.
Sasuke has shown to manifest many different shapes with his Amaterasu and Enton variants. Mei and Tsunade have not shown to be of the faster caliber Shinobi, and as such, don't have sufficient reaction feats to lets say.... Dodge an Enton Arrow? Said arrow had to be countered by Kamui (Kakashi) or he would have been gone. This is the same Kamui that was able to dislodge the entire arm of the Gedo Mazou of the Juubi in a split second before it was instantaneously reverse summoned via "Kuchiyose No Jutsu" by Uchiha Madara [
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][
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]. Needless to say, they are absolute non-factors in this fight, and are easily dispatched making this fight a 3 on 1.
Ohnoki is the only person of the Kage that can damage Sasuke's Perfect Susano'o, much like his abilities were utilized in their battle against Uchiha Madara. However, Ohnoki, even with flight, is a sitting duck to Amaterasu (not to be confused with Enton). The only people who have actively dodge Amaterasu are Ei because of his speed (and the only ones who rival or surpass are Uchiha Obito, Uzumaki Naruto, and Namikaze Minato) and Juubi Jinchuriki Obito via sensing [
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]. Ohnoki possesses neither of these and therefore is susceptible to a blatant Amaterasu strike, one to which he possesses no ability to negate or evade.
Gaara is one who is the only person that can actually sponge any attacks from Sasuke, but there is a fatal flaw... Uchiha Sasuke's Enton Sword used with his agility in his legged Susano'o. [
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]In just that form, Sasuke was able to take out a massive chunk of the tree with a quick swipe. That being without Enton added to the sword. With Enton and the veracious agility he seems to display with Susano'o, repeated swipes with Perfect Susano'o and an Enton Sword would eventually break through Gaara's defense and finish off the Kazekage.
And to people disregarding the fact that Sasuke has Perfect Susano'o... [
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]. Madara's Susano'o clearly has the elongated nose on his Tengu demon.
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Sasuke clearly has the same Tengu, AND the same sheathed sword
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which Madara possessed on his Susano'o as well. And to further validate this, Sasuke exclaims in the previous panel that "
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". And before discrediting the size, Perfect Susano'o has taken on a different shape each time it has been fit around the Kyuubi. Sasuke had to literally coat Kurama (Naruto) and was around it, as opposed to it fitting closer to size. Same with Madara [
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]. Both times the larger Susano'o had to be fitted to the smaller Kurama. So with this definite evidence of Sasuke possessing Perfect Susano'o.... Ei is not much of a problem at all. His fighting style is negated by the massive construct and he, along with the rest of the Kages will be annihilated if they haven't already before this.