In the beginning, Primus and his brother, Unicron, was created. Unicron felt all life besides him and his brother were inferior, and decided that he would destroy it. Primus was against it, and battled him in a duel, where Primus won. Primus created the AllSpark, and was the first Transformer, transforming into Cybertron, and letting his race take fate in it's own way. Unicron floated across the Universe as a Planet-Eating planet, and waited for his revenge against Primus, his creations, and the Universe.
Meanwhile, eons later, the Decepticons return with one idea: Destroy the Autobots. The leaders Optimus Prime and Megatron battle on the Planet Earth, a legion of loyal (and treacherous) troop. Now that humans are aware of the Transformers' presence on Earth, humans have had many mixed views about the aliens sharing the planet that they call home, especially since the Autobots and Decepticons have made Earth their battleground. Even though the Autobots are good and noble, there are quite a bit of humans who hate them as well, mainly because of the bad name Decepticons have given their kind.
A human, Sam Witwicky, has yet another vision from an AllSpark fragment, and sees a Planet-Eating monster, who does battle with another Planet-Sized Robot. Then he sees the Planet-Eater heading to Earth.
Optimus realizes this means doom, and asks Megatron for a temporary truce and that they help the Autobots in their attempt to defeat Unicron. Megatron does not believe Prime, and continues battle. Unicron, meanwhile, heads towards Earth to destroy The Transformers, due to The Fallen's destruction, his herald and Primus's traitor...
Later, Wheeljack finds Transformers locked inside the La Brea Tarpits. They emit neither Decepticon nor Autobot energy, and he is interested. He and Hound dig them out, and they discover they are the Dinobots, Transformer that transform into Dinosaur modes, led by Grimlock. The Dinobots received damage, and do not remember their past and speak in a rather bad grammar language. Optimus Prime tries to convince the Dinobots to join the Autobots, but Grimlock disagrees, especially since his group of Transformers are highly independant and hate being told what to do.
Sam unintentionally provokes a fight when he angers the Dinobots by calling them stupid and stubborn fools.The Dinobots are enraged by this remark and attack Sam. Bumblebee, Sam's closest Autobot friend who is always eager to aid his friend, immediately intervenes and protects him. The tension escalates into a full out brawl between the two factions.
The Dinobots emerge victorious proving their strength, and go on a destructive rampage to vent. The Autobots wish to pursue the Dinobots because of this once they stop the rampage, but they don't at the request of Optimus who says that there are bigger things to worry about.
Soundwave sees and hears the Autobots being defeated by the Dinobots in battle and realizes that they would be perfect for the Decepticon army with their brute strength. Soundwave alerts Megatron of this news, who is very interested in finding minions who can defeat Prime. Megatron takes several Decepticons and flies to ___________ *wherever the Dinobots are at at moment xD* >>>
Unicron approaches Earth, and readies to consume it, crashing through the Asteroid Belt. The Autobots have no choice but to defend Earth and to make a last stand against Unicron on their own.
Megatron tries to persuade the reluctant Dinobots into siding with them, telling them that they should be angry with the Autobots for not getting them out of the tar sooner, some lies and bullcrap, ect the works. But the Dinobots refuse to serve for anyone and ignore them. The Dinobots are walking away from Megatron and enraged that they turned down his offer, orders the Decepticons to attack. The Dinobots transform into their alt modes and they battle, ending with Megatron losing several minions and retreating with the remaining Decepticons that survived the battle back to his main army.
While Megatron is trying to persuade the Dinobots to side with the Decepticons, Starscream contemplates to take over the Decepticons. Soundwave hears this, and reports to Megatron as he is retreating back to his main army.
The Autobots have no choice but to defeat Unicron themselves. Megatron learns of Starscream's plans and looks for Starscream.
Upon his return, Megatron finds and sees Starscream plotting in the act, confirmation of his treachery and betrayals, and effectively destroys Starscream, and appoints Shockwave his second-in-command.
The Decepticons see Unicron, and realize that Prime wasn't lying. Megatron agrees to help Prime against Unicron, but only because the joy of destroying Earth and the Autobots is his alone. However even with their combined forces they are still no match for Unicron. All seems lost until out of nowhere Grimlock arrives leading the Dinobots after coming to his senses and realizing that the Planet would be destroyed with them on it.
Once the Autobots return to Earth's surface after successfully defending the Earth, the humans accept and congratulate them finally for their achievements and all of their help they've been giving all these years in disguise. Now loved, the Autobots have finally earned their place on Earth in the human's views. =U The Decepticons meanwhile, are still hated. :3
End of Story has Unicron's Head floating in space... His eyes open. O_O