If Sasori gets blood, the other guy is dead anyway....Hidan and sasori for the win.....
For Sasori it is quite easy to get blood, maybe by using his weapons, 100 puppets or even iron sand techniques would allow him to get blood samples, in order for Hidan to make the finishing blows.
Anyway I like Itachi + Pain, not because they would be OP but because they would have very interesting conversations.