I think if unicron was in any movie he'd have to be a planet and have a g1 esc robot mode, but what would be his purpose?maybe in tf5 optimus find the quints and sees there building him then kills the quints but its to late so he takes a ship back to earth along with ultra Magnus hot rod KUP and blue and tells the AUTOBOTS seeing that side swipe is still alive and sun streaker has joined the part mean while galvatron is up to stuff and unicron calls him giving him troops to kill prime and making him a real TRANSFORMER. Also how would hasbro make him a toy?
If Unicron was in the movies, I don't think he would be a planet sized robot. Although that would be sweet, I highly doubt it. Unicron in any size would be fine for me. As long as he is extremely powerful. The Fallen is the closest thing we have gotten to a Unicron so far.
Yeah there's absolutely no realistic way to do him as a planet. I mean they could literally have the planet and the rest of the characters on it, but there's no way they could possibly have him in robot mode and in shot with anyone else visible.
my favorite possibility, and I can't remember who had the idea so I don't know who to credit, but I like the idea of him just as this entity that gets into peoples/robots minds to drive them crazy and gets them to do all kinds of evil shit. basically trying to get everyone to tear each other a part
