@itachus17: actually, They should at least be above Konan. Konan's real danger is when she's prepared and underestimated. Hit her with oil, fire, or both, and she's done.
Kakuzu is tougher and more difficult to take down, since he has to be killed five times over. And you have to overpower the earthspear five times. Other than the giant mecha, they won't beat him in strength, but even that's debatable.