Here is a plot that I came up with that would introduce Galvatron. Transformers: Rise of Galvatron: Long ago, Primus and Unicron came into being as natural consequences of the universe's will to balance itself Primus came into being as a creator, but Unicron came into being as a destroyer Primus created all planets and forms of life, but Unicron destroyed many of them Realizing that Unicron exists solely to work against him, Primus battled with Unicron and sealed him away in a resting place similar to his own This resting place is known as Megamax Primus then created Cybertron to serve as his resting place, at the center of which he rests as its core (i.e. Primus is the core of Cybertron) Primus created the ALLSpark to re-energize Cybertron when necessary and create the Transformers to guard Cybertron Awakened by the partial destruction of Cybertron, Primus emerges from the center of Cybertron and transforms from his planet-core mode He warns the remaining Transformers that his energy-signature will rouse Unicron from his slumber. Unicron, roused from his slumber, calls out to the Decepticons Unicron has a special connection with the Decepticons because it is he who corrupted Megatronus Prime, turning him into The Fallen (the first Decepticon) Unicron calls out to Straxus, ordering him to come to Megamax with Megatron's spark There, Unicron orders Straxus to place Megatron's spark into a newly formed body and then reveals to him the Dead Matrix He then orders Straxus to use the Dead Matrix to animate this new body, into which Megatron's spark has been placed This newly animated being is named Galvatron Galvatron becomes the leader of the Decepticons, kickinig off the next saga
I could see this working if it was expanded upon and storyboarded. I'm kicking around a few ideas like this as well and I'll make a thread about my ideas as soon as I can.