In the year 21XX, the good Doctor Celestia created the first Pwndroids to protect the humans of earth, and to perform duties which were too difficult or dangerous for fragile human bodies. It was a Golden New Dawn, Dr. Celestia even created for her self 3 pwndroid children. Scoot@loo, Apple Boom, and Sweet-e Bell. It was a time of peace and prosperity.
Unfortunately her beloved sister, Doctor Luna, believed humans were weak and corrupt, a danger to them selves and their world. After seeing the product of her labor abused and mistreated, she declared that humanity must be saved from it's self, by being ruled by a new mechanical empire. The war between the peace loving Solar Empire, and the mechanical Lunar Republic was long, and bloody. Finally Dr. Celestia had no choice but to corrupt her beloved children into weapons of war. Scoot@loo would not let her kind hearted sisters be changed in such a way, and volunteered her self. As the flames of war raged, Scoot@loo entered the augmentation chamber, and fell into slumber.. Awakening as something new, determined, and terrible, the first Megapony was born.
In the end, the Megapony was able to cut through Dr. Luna's mechanical armies, and defeat her inside her armored stronghold.. Dr. Luna realized she had been wrong all along, and devoted her life to mending her terrible mistakes.. But Megapony and Scoot@loo had become one in the same entity, their identities now inseparable. Realizing there was no long a place for her in this world, she re-entered the augmentation chamber, and drifted off into peaceful oblivion, praying the day would never come when she would need to be reawakened...
Many years have passed, mostly without incident... but a long forgotten fear has begun to spread.. Rumors of a virus, known as D15C0rd corrupting the neural nets of Pwndroids, turning them against their human counterparts... The long buried cinders of war are beginning to spark back to life... and it is only a matter of time until Megapony shall be needed again...
Rainbow Crash (air fortress. Weapon; Rainboom Cannon), Twilight Spark (power plant. Weapon; Telespark), R@r1ty (manufacturing plant. Weapon; Tom), Apple Crack (Industrial Farming Plant. Weapon; zapapple), Pink-e Pi (Food Processing Plant. Weapon; party cannon) FlutterWry (Anim-droid manufacturing Plant. Weapon; Paralyzing Stare) Spyk (Library of the Two Sisters. Weapon; Fire Flash)
...............I could do more........But nobody will have read any of this as it is, so why bother..
Oh, and a quick critique. Her hooves are slagging fuggly. I'm liking the basic idea you're going for with them, and especially like the fins on her forelegs, but the tippy-toe forehooves are structurally unsound in walking mode, and her afthooves are ascetically unpleasing to the eye. And where the Hay is her tail?