honestly i dont see any way for oro to dodge dust release properly, if he brings out any edos before he gets hit then it ends as a draw but other than that no...The only way Oonoki wins as far as I can tell,is with his Dust Release. So if he can land his one-hit kill then he wins.
If the fight is toe to toe and drawn out,then Oro...
Wow, so much wrong with this. During the battle with 4 tails Naruto, Oro shed his body (Body Shedding), not substitution jutsu. And Oonoki used the Akatsuki many times, meaning that he probably employed or at least knew of Orochimaru, so I don't think Oonoki would underestimate Oro. Oonoki would win because of Dust Technique. There is no way Oro could heal from that. Plus, Oonoki can use all the elements Oro can, plus fire.Orochimaru was fast enough with his substitution jutsu that even Naruto with 4 tails couldn't hurt him. Let's just assume that Gaara isn't there to motivate Oonoki, or Madara to remind him of his youth- Oonoki won't be whipping out dust style jutsu that can destroy villages, or catching meteors with his bare hands. He'll be complaining about his back and underestimating Oro. Meanwhile Oro will have Manda summoned, his 7 headed serpent jutsu, and the grass longsword.