Darui defeated the infamous Gold and Silver brothers in Edo formation. These two shinobis were strong enough to rage havoc on the peace treaty ceremony between the Second Hokage and the Second Raikage, the two brothers staged a coup d'état that left the Hokage on the brink of death. If they can do that to a hokage, this can only mean that they are insanely strong.
Kurenai Yuhi. B-)