Even without legs Sasuke takes this.
1st of all, going under Sussanoo will not be effective, if the technique is not light enough(Which Onoki help Gaara do it in the first place[
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]), or strong enough, to attack underneath. Something Gaara has not display alone. So no legged Sussanoo can still use a chakraboard just like what Madara had done without touching the ground[
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]
2nd Current Gaara has still shown to have trouble catching speedsters[
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], which shows how slow his techs are and relies on quantity to be effective, of capturing/defeating.
Sasuke could always use Summonings to beat Gaara's Sand. Aoba is perfect since it's slick and pretty fast[
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] dodging any Sand devolving, to get a hold on to..
Since Aoba doesn't have legs to begin with, Sasuke can materialize Perfect Sussanoo on Aoba, making this fight over (Materializing PS is not even needed and could do this[
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] and[
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] the whole time on top of Aoda.
Sauce wins low dif.