The battle between Primus and Unicron is fought not only in the physical universe but also on the mental plane. Damage inflicted on the plane can be felt on the physical and can reslut in complete shutdown. Assuming the role as protector of the universe, Primus used the energy the One had given him to attack Unicron directly, the forces clashed explosively and repeatedly. like unicron Primus has two modes a planet and a robot. this planet is called Cybertron and he passed this transformation ability to his children the Transformers.
In this series, Primus was ressurected by Optimus Prime and the Autobots by the power of the Omega Lock with the 4 cyberplanet keys, in the final episode we see the 4 atlantisis from the Jungle Planet, Speed Planet, Gigantion and Earth combined together into a gun that Primus uses to stop the black hole.