I don't believe we've seen anything yagura has that can counter hanzo's poison. But then again he was defeated by someone who isn't even a ninja so Yagura I guess.
We do have enough feats, Hanzo beat all 3 Sannin at one point without a scratch and his poison is ridiculously hax. Yagura really has no choice but to breathe it and he's not necessarily the best fighter out there. Ibuse and Hanzo stomps.