The Transformers obviously has no story. Only rules, like your game of Monopoly or Ludo:
1. Autobots are good alien robots.
2. Decepticons are bad alien robots.
3. The cube is ultra powerful.
4. Sam Witwicky is horny and noble.
Now play! And Don't. Look. For. A. Story.
Of course, when stories and plots and logic and similar such party-poopers aren't there to pull us down, it's a rather fun ride. Apart from an irritating tinnitus of Pentagon-Pentagon-Pentagon in your ear - and all the applesauce about the fate of human race - the movie is pretty shamelessly lightweight.
There are times when the Autobots confer with each other about how the human race is young but shows promise, or when they solemnly condole the death of their brave comrade - times when you are reminded of a 5-year-old kid trying gravely to mimic his dad - but otherwise the Autobots slip away gaily into cheerful mayhem. They turn into zippy cars and large fiery trucks, pee on offending humans, speak in urban slang, and one of them even does a mean break-dance.
Once they begin buffooning around, there is no stopping them. Imagine half-a-dozen stooges in the guise of complex, giant robots, bumbling around, hiding in people's backyards while they are not saving the world - they'll tickly you silly.
Shia LaBeouf as Sam Witwicki comes back in a repeat of his role in Disturbia - that of a pheromone-driven, hyperactive teen, his nose helplessly on the trail of tanned bombshells in the neighborhood (Megan Fox as Mikaela). His antics are riveting as he zips through the movie, dribbling along Mikaela in her form-fitting, cleavage enhancing outfits, while helping the bots save the human race.
Undoubtedly, the funniest takeaway from the movie is Sector Seven - the mysterious, Secret-Service-like undercover organization that discovers the first Decepticon to land on earth, and hides it in its basement - under the Hoover dam. Funnier still is Agent Simmons (John Turturro) who wears Sector Seven underwear that has a Superman kind of logo and flashes his "Do whatever I want and get away with it" badge in the face of every kind of trouble.
They weave acronyms (NBA for non-biological aliens) on the fly, dealing as they are with diabolical robotic species. And in the end, they face a humiliating defeat at the hands of the more powerful US Army and Air Force which takes over once it discovers their crackpot endeavors under the dam.
That's about all the 'facts' you need to get you through The Transformers, but if you still insist on a story, well, here is what the scriptwriters throw at you. On a planet far far away called Cybertron, live two species of shape changing robots - Autobots and Decepticons. These robots ain't anything like our own homegrown rickety Asimo, mind you - each is as elaborate and bulky as a Venetian chandelier.
Autobots have a preference for turning into cars (mostly swanky, but sometimes 'piece of crap' Camaros). Decepticons fancy turning into more evil-looking critters - scorpions and other multi-legged, shrieky-voiced creatures.
The two species fall out in trying to own a powerful, energy-emitting 'cube', and leave their destroyed planet in hot pursuit of it as it floats around in space, finally finding its way to earth. Waiting on earth are Sam Witwicki and his car-mechanic friend Mikaela (she fixes car engines since she cannot just be a dumb bombshell), who then chaperone them around to victory over Decepticons and the threat they obviously pose to the human race.
Makes no sense? Well, it was never supposed to. Just let loose the non-judgemental, gizmo-loving, schoolboy inside you, and bumble along with the movie. You will find out soon enough that superficialities like stories and plots don't always make blockbusters. Giant buffooning robots and hormone-numbed teenagers can make good substitutes.