Well, it can be one of a few things depending.
Either before the 2007 Movie with a group of Decepticons Searching for Megatron and the allspark.
Or After the 2007 Movie, with the Allspark gone the Decepticons are looking for an alternate source of energy, but unlike the Team from the movie, their journey leads them to another source of power, this one coming from a human source. (Whether it's harvesting humans for energy or just stealing their nuclear energy, it can really be anything.)
-Main Autobot Squad-
Billy Rid, 1935 Ford Pickup Truck - http://i10.photobucket.com/albums/a139/OHWceta/references/BillyRid.jpg
- An old veteran in the cybertron war, he's well trusted for his mission by Optimus Prime. He has a tough exterior but a caring spark and will fiercely protect his team at any cost.
Hard Rock, 1998 Isuzu Amigo - http://i10.photobucket.com/albums/a139/OHWceta/references/Hardrock.jpg
- The rookie, Impatient and feisty, Hard Rock is always looking for the next fight and often times bites off more than he can chew. He tends to speak before he thinks and is often scolded by the older team members. Though Billy Rid sees in him a great warrior with much potential.
Scuba Kat, Diving Catamaran - http://i10.photobucket.com/albums/a139/OHWceta/references/ScubaKat.jpg
- A loyal friend of Billy Rid's he's an information specialist and scout, one of the first to arrive on Earth. Though his fighting capabilities leave him limited he's an expert at long range.
Rain, Pontiac Aztec - http://i10.photobucket.com/albums/a139/OHWceta/references/Rain.jpg
- Rain has always been considered ugly by the other autobots leaving her confidence lacking. But Billy Rid doesn't seem to care, he values her as a top fighter suited well for this mission. She has a romantic interest in Overgear.
Overgear - http://i10.photobucket.com/albums/a139/OHWceta/references/Overgear.jpg
- Overgear is a tough but gentle giant, he prefers peaceful solutions but will fight when needed. He is usually tasked with supplies and maitenance. His calm and patient attitude is often at odds with Hard Rock, leaving the two to constant bickering.
Skyhigh, Biplane - http://i10.photobucket.com/albums/a139/OHWceta/references/Skyhigh.jpg
- A former criminal on Cybertron, Skyhigh is reformed in his ways, joining the Earth crew of Autobots to make ammends for his actions. He is a master scout and skilled spy.
360, Xbox 360 - http://i10.photobucket.com/albums/a139/OHWceta/references/360.jpg
- Due to his small size, 360 rarely fights and is usually tasked with gathering information and infilrating areas where others can't reach. If they must interact with humans it is also the job of 360.
-Autobot Reinforcements (mostly one scene or short appearances later in the story)-
Flak, Yellow Ford focus Hatchback - Quick witted and wiley, Flak is a good friend to Hard Rock, though less intent on action, he is a skilled messenger and often transports small goods from one location to another, when you want something done fast, call Flak.
Ringtone, Silver and Blue Razor Cell Phone - Aside from Billy Rid, Ringtone is the only other member of the team who has actually met Optimus Prime face to face. Ringtone is tasked with finding Billy Rid's team and establishing contact between them and the Autobots on Cybertron. But for his small size, getting to them will be no easy task.
Sky Rush, Space Shuttle - http://i10.photobucket.com/albums/a139/OHWceta/references/Skyrush.jpg
- Leader of the Decepticon team, Sky Rush hides in orbit of Earth as he searches for his goal (Depending on what plot we're going with) He sends his orders to the smaller more easy to hide members (Aside from Tidal wave who is a whole lot larger), waiting for his time to drop from orbit and finish the Autobots once and for all.
Air Raid, Stealth Bomber - http://i10.photobucket.com/albums/a139/OHWceta/references/AirRaid.jpg
- Sky Rush's second in command, he eagerly hunts the autobots with a sadistic glee. He loves to cause enemies pain and hear their metal grinding as he rips through their armor. Surprise attacks are his specialty and he has a strong hatred of humans.
Heat Index, Fire Truck - The opposite from what you'd expect in a firetruck Transformer, Heat Index is something of a Pyro, using attacks that melt the frames and circuits of his enemies. He finds humans a mere annoyance and sometimes he questions why he's still fighting in this war. But he'd never betray his master.
Payload, SCUD Missile Carrier Truck - Payload couldn't have any more of an annoying partner, the Quiet Beast lumbers on. His fighting style is powerpacked and slow, he's not likely to hit you but when he does you're in for a few broken limbs.
Crackshot, SCUD Missile - Wild and Talkative, Crackshot specializes in long range combat, He has incredibly hight indurance due to his Kamikaze nature and is the Movieverse Equivilant of Beast Wars' Waspinator.http://i10.photobucket.com/albums/a139/OHWceta/references/PayloadandCrackshot.jpg
Viper, Dodge Viper - http://i10.photobucket.com/albums/a139/OHWceta/references/Viper.jpg
- One of Cybertron's top assassins, when all else fails to kill Billy Rid, Sky Rush hires him to bring down the Autobot team.
Phantom, Z3 BMW - http://i10.photobucket.com/albums/a139/OHWceta/references/Phantom.jpg
- Number 2 on Cybertron and Sky Rush's 'insurance policy' with Phantom and Viper on his side, nobody could hope to survive an onslaught from the duo.
Agent Silver, Caddilac Escalade -
Agent Black, Caddilac Escalade -
It is unknown how many Agents Sky Rush Actually has but he always has two constantly tracking down the Autobots. (And only 2, they seem to get killed in almost every fight but come back againhttp://i10.photobucket.com/albums/a139/OHWceta/references/Agent.jpg
(In Black and Silver Respectively)
Brutus, Combine Tractor - http://i10.photobucket.com/albums/a139/OHWceta/references/Brutus.jpg
- Brutus is a peaceful beast. The only reason he even joined the Decepticons was because he was an outlaw in Autobot Territory. Sky Rush thought he'd be a powerful ally on the team but he turned on them on Earth, fleeing and vanishing into the unknown somewhere. All he wants is to be left alone but the war keeps finding him. He has a curiousity for humans and a love of Organic life.
And then one Canon character who i've always wanted in Movieverse
Tidal Wave, Aircraft Carrier - The big rather dumb brute but unmatched in size and power. When all else fails to defeat the Autobots Tidal Wave is called in as a last resort.