The robot thing that Nagato's in is like Sasori's puppet. In fact Nagato's 6 paths are like Sasori's puppets too. More over, Nagato is a cripple just like Sasori is without his puppet. So now that the 6 puppets are out we'll get to see the robot puppet in action. The robot has 6 legs which means it's designed for battle but much stronger than Sasori's wooden puppets.