Back to Its Roots
Long ago, back near the human races very beginnings the world was pure. Humans and pokemon coexisted peacefully, battling was unheard of. Humans rarely even took pokemon as companions, but a similar practice was used. Seconds after a human was born the Legendary Pokemon bestowed upon them shapeshifting abilities. Each was given the power to morph into one species of pokemon, either fully or into a hybrid form. As technology grew and humans bond with the Legendaries died away, the practice faded, giving way for the sport of training.
Recently technology has, in a sense, taken over the world. The Devon Corporation has become the leading organization across the world having bought out most of its competition including Silph Co. Factories are constantly being built polluting the planet and destroying the wilderness. The new president of the company couldn't care less about the welfare of the world; he's just after the money. He's hired Team Rocket to stop any protests and to destroy any competition that arises.
Obviously the Legendaries are not happy about this. They have decided to give a select group of people the powers they had used to give to everyone. These humans are to rebel and fight back against the rising empire that is Devon. The Legendaries want the world returned the way it once was, in the time of peace. Will these few be successful in their mission and restore the world to its former beauty or will they fail at the cost of the planet itself.