- Motto: "A rainbow of adventure in every can!"
- Weapon: 16 Cannons
Personally, my choice would be to set up Unicron as the major villain, but with the idea of keeping him off-screen until the third movie (assuming it's a trilogy), or maybe the end of the second one.
Spend the first movie with the Autobots fighting against his herald, who I would LOVE to be Nemesis Prime. And- thinking in terms of selling toys- if Nemesis Prime were a Unicron-controlled Optimus Prime, Hasbro could bring in Rodimus to replace Optimus. Then the second movie would be something like Nemesis bringing back more of Unicron's heralds or something, and the third would finally be the face-off against Unicron, along with the inevitable Optimus regaining control of himself and sacrificing his life to defeat Unicron, blah de blah de blah. This would not only create an overflow of suspense and longing and make everyone really excited for Unicron to finally show, but it would give the animators a long time for technology to advance so their computers wouldn't melt when it was finally time for Unicron to come along.
The one downside I see with having Unicron is that Hasbro'll probably want to make even more movies after that. And where do you go after the giant planet-eating monster? Anything else is kind of a step down afterwards.
...Or hey, Shattered Glass. That might be fun.