TF4 = Heralds of Unicron.[/b] The Space Bridge Dark of the Moon allows travel through time and space, actually sent the majority of Cybertron back in time and far across space, twisted the inhabitants, merged many of their sparks and created UNICRON!
The modern time warp finally makes Unicron aware fo the location of the planet of the humans that caused his pain(Earth, duh) and he sends his heralds to go prepare for his arrival.
Part of the preparations is the gathering of dead protoforms on our planet (Unicron needs the extinguished sparks as he cannot manipulate functioning ones).
Dinobots and Insecticons get introduced as having been buried on this planet for centuries, lost at the time of the Primes (their workers on the Harvester) but their Protoforms can no longer change and they have traditional gold/gray/red and black/purple/yellow coloring due to not having a lot of options on how to repair themselves from being trapped on Earth and are uncovered by mistakenly being thought of as dead.
The factions are treated almost as religious factions (by emphasising the choice that they make on who to side with) and many Decepticons help the Autobots as they feel the taking of Megatrons Body to be Sacrilege. The Autobots and a small band of Decepticon allies beleive they have defeated them at the end.
TF5 = Unicron Approaches. Unicron's newest (most powerful) heralds are created and dispatched, these would be Galvatron and his Sweeps (the sweeps ore not countless Scourge clones but individual characters).
In answer to the power that is Galvatron and the Sweeps, Ratchet creates an exoskeleton ("Ironhide would have loved to get his hands on that"). A small ship of religious and pacifist Autobots arrive led by their Magnus (a religious title like a Bishop), Dion (one of the crew is a young, but not childish Autobot named Rodimus). Prime is heavily damaged in battle and Dion realizing that pacifism is not working merges himself with the Exoskeleton to become The Ultra Magnus.
Unicron arrives at the edge of our Solar System and destroys the pacifist Autobot base on Pluto. It ends where Galvatron is damaged and the control Unicron has on him broken, Ultra Magnus is also beat up really bad, Optimus is beat down but healing, and Unicron is looming.
TF6 = The Battle of Unicron. Unicron arrives at the moon. Galvatron decides that he is again Megatron (having had control broken in 5), and wants revenge against Unicron for trying to control him.
Galvatron also wants revenge against the Prime and the Autobots for killing him, he splits his forces against the Autobots and Unicron and Prime has to do the same in Defense. Ultra Magnus commands the Earth bound troops fighting the Decepticons, but after a major defeat realizes he is no military leader and allows a young Rodimus to take command.
Prime leads the assault on Unicron and after fighting each other to a stand still, Megatron realizes his vendetta against Unicron is priority (he can kill Prime later, but needs a home for the time being). He takes Prime to the Harvester, but attacks him from behind in an attempt to claim the Matrix (which will activate it) for himself.
Just before Megatron can use the Matrix (with other plans to use after Unicron), Rodimus arrives, reveals himself to be a decendant of the Primes (there's a shocker), battles Megs, retrieves the Matrix and Uses the Harvester to destroy Unicron (as "YOU GOT THE TOUCH..." is playing in the back ground).
I got more ideas and would be happy to contribute to the production freely, I don't want any credit, I'm a fan, I just want to see these made!
I've only told a couple people these ideas and have been dieing to share.