My 2 Cents is this...
Remember when everyone was trying to save Gara. And team Kakashi and Gai were both stopped by Itachi and the Kisame (I believe thats his name). They used a technique where they turned a person's body into their own, and Kisame even said, "We only gave them ___ % of our power."
Why couldn't Itachi use 80% of his power and transfer it to 4 people??? Wouldn't that make him just like Pein!??! What is the true technique Pein is using here???
What if that is Pein's technique? He is the medium sitting there meditating, and commanding each of those 6 people's bodies. The reason that they look different could be due to some experiment Orochimaru used to preserve the bodies, and prevent them from decomposing.