[Sentai]

The story itself I'm enjoying how it is. The only thing I'd change is Robo Knight. And how his origin came into play. Instead of a Robot from Who Knows Where... I'd go with this:

After Zordon was killed by Andros, Gosei knew one day it would be up to him alone to save Humanity. And choose a new team. But he didn't want to put the people he was meant to protect in danger, so he used most of his energy to create a Knight. Gosei Knight. But Gosei Knight was broken. His main directive was saving the World.. and he saw Humanity harming the Earth through pollution. He started attacking the people and Gosei knew he needed to stop him. So Gosei used all of his remaining energy to banish Gosei Knight into the Arctic. Forcing Gosei to take the shape of an Idol to replenish his energies.

But when the Mutants rose Gosei knew the Rangers needed help. So Tensou, Gosei's second attempt at making something like Gosei Knight, travelled to the Arctic and freed Gosei Knight. Who resumed his mission... Can the Rangers turn him to the side of the Humans?!