Poison doesn't affect orochimaru.
I was going to say the same thing as well. Orochimaru can be cut into peices, and can still reform his entire body, as well as shed his skin.
He can also take the sword of his and impale Sasori from long-range, That's right, I said
LONG RANGE.
Orochimaru can take on Sasori's 1000 Puppet Jutsu can can still wipe them all out. If he notices the 2 puppets with Sharingan, he can also take those as well, and after maturing his Sharingan into a Mangekyo, he can then transplant the other Sharingan into his eyes and store his Mangekyo until he mature those into Mangekyo, then transplant the other pair into his eyes again, then gain an Eternal Mangekyo, the do what he does and Mature that until it evolves into Rinnigan, achieving his ultimate goal over halfway, then he can work on learning all ninjutsu!
I'm sorry I got a little carried away with the Sharingan, MS, EMS, and Rinnigan thing, but it's completely possible!
Anyway, I think Sasori can't compete with the 1st and 2nd hokages together, let alone 1 on 1.
KABUTO AND OROCHIMARU TAKES THIS WIN!