Each bodies have it's own specific purpose and jutsu. They all haverinnegan eye, piercings and share the same sight. One body can detectopponent movement for the other so attacking Pein's blind spot on theback is impossible. Jiraiya said that he had seen all these host bodybefore during the encounter with Pein.
Pein's first body (Yahiko), mainly used water element jutsu such as chakra sensing rain fall.
Pein's second body (Fuuma clan), mainly used animal summoning techniques in the attack.
Pein's third body that were summoned later, this thin body used taijutsu in attack and defence.
Pein's fourth body which was summoned the same time as the third body, this fat body used ability to absorb any chakra attack.
Pein's fifth body, primary use long range attack.
Pein's sixth body.