Let me explain what we don't want. We don't want human leads. The leads are Optimus Prime and Megatron. We don't want a romance subplot. The core plot is robots blowing the shit out of each other. We don't need fancy jigs danced around the names. Bumble Bee is not a Camaro (I know VW wouldn't license the Bug, but to go from a VW Bug to a CAMARO?), Devestator is not a tank. Don't try and placate us by saying that those names are temporary.
You know who should be directing this movie? David R. Ellis. You might know him as the director of the best movie ever. Why do I suggest putting the director of Snakes on a Plane in charge Transformers? Because both of these films have incredibly simple premises. In one, there are snakes on a plane. In another, giant robots go rampaging through a city. Simple, pure things that harken back to our child hood. These are not plots made as richly woven tapestries. These are straight-line-a-to-b stories. These are stories that are meant to appeal to the least common denominator and be good at it.
Let me give you my plot sketch for a Transformers film.
We start on Cybertron. All of our Transformers are very sci-fi, they convert into strange vehicles. Optimus Prime and some other transformer handle some exposition as they try and stop Megatron from reaching his ship. "We all need Energon, but we've got to stop the Decepticons from getting it!" They fail, and go for plan-b- but they'll never catch up in time. Some Captain Kirk-esque "Like hell we won't!" from Optimus gets them there in Earth orbit. The two ships go broadsides, and the Decepticons board in a piratesque manuver. I want to see robots flying through space with magnetic grappling hooks! Both ships crash. At this point, you should recognize this much of the outline- it's the start to the original series.
A million years later. An earthquake awakens Teletran 1, who scans the nearby area for suitiable templates for the reconstruction of all of the Transformers aboard. The Decepticons awake first, and Megatron moves to finish Optimus Prime. Let's say that, for the movie, Megatron is a GIANT FUCKING CANNON. Okay? Super-howitzer. Megatron gets the gun right up into the non-functional Optimus' face, when the internal defense grid comes online. Soundwave (again, let's not address the scaling issues- soundwave isn't just a boombox, he's a full stage setup for a DJ, and comes with a mini-robot to fill that role) pulls Megatron out of the way of a laser blast, and the Decepticons beat a retreat.
END ACT I
In Act II, the Decepticons set it as their main goal to get back to their ship, which crashed in the ocean, but to get there, they're going to need Energon. Megatron orders Starscream to do it, and Starscream, somewhat annoyed, takes his jets and performs the task- in this case, raiding a nuclear reactor. But along the way, Starscream passes some signifigant natural landmark- perhaps Meteor Crater or the Grand Canyon or something- and realizes that this is a legendary planet. Millions of years prior to the start of the Great War, a massive battle took place here, and it left behind it a Transformer with an indestructible spark named Rampage. The unkillable Transformer. The Frankestiein monster of Transformers- whoever controls it controls the war. Starscream sets his goal on finding and ruling that beast.
The jets arrive at a nearby nuclear reactor, and Teletran 1 alerts the Autobots: "Roll out!" The Autobots race to the site, and get in a fight with the jets- who promptly retreat with enough Energon to power them until they can reach their ship. The Autobots befriend some humans, and that's the last we see of humans for awhile.
Megatron is suspicious of Starscream, but is willing to wait and see if he can catch Starscream red handed. Soundwave sets Lazerbeak to track Starscream.
That's all I can bang out for now, but I think this shows how simple we can make the premise here, and that roughly maintains continuity with the mainline Transformers as well as Beast Wars. And breaking Rampage out (not as a crab, but as some hideous mixed beast) would be fucking bad ass, especially when he gets unleashed on a city.