The Seasons Of Power Rangers: 1990s
Part One
Power Rangers: Supersonic Squadron (1990-1991)
The scientist Dr. Hawking’s is working on ways to bring life to barren planets. Just when his labours seem to be bearing fruit, the planet he is on is attacked by the Minus Empire. His five children escape the planet safely, thanks to their robot, Arthur, but Dr. Hawking’s and his wife do not manage to get away from the planet. Twenty years later, the children have grown up, and are now elementary school teachers when the Minus Empire comes to destroy Earth. The children use their father's inventions to become the supersonic squadron and fight against the Minus Empire and save Earth.
Power Rangers: Bird Fury (1991-1992)
In the year 1991, an international defence agency called Skyforce creates a method to develop Super Soldiers by infusing humans with "Birdonic Waves". Five of the best Skyforce officers are chosen as the first subjects; unfortunately, the experiment is interrupted when an army of Alien invaders known as the Morphatine launch a surprise attack on Sky force’s orbital base. Four of the five Birdonic Waves fall to Earth and strike four random British civilians, imbuing them with superhuman power. Skyforce must recruit and train these ordinary people to fight against the Morphatine as the Earth's last hope: the Bird Fury Rangers.
OTL: Choujin Sentai Jetman was considered to be the first series of power rangers.
Power Rangers: Preastoric Beast Squadron (1992-1993)
200 million years ago, humans lived in peace with prehistoric animals, until the evil witch Calder appeared, killing the dinosaurs, and began to attack humanity. The Guardian Beasts, great gods sealed her away on the moon. In modern times, astronauts exploring the moon accidentally release Calder and her followers from captivity, and she again starts to attempt to kill humanity, starting with the children. An ancient wizard in disguise as a building superintendent releases five warriors from the five prehistoric human tribes from suspended animation to fight Calder’s forces
OTL: Kyōryū Sentai Zyuranger became Mighty Morphin Power Rangers in the U.S