Definitely the Power Rangers RPM themselves. They are the heroes in their own story, so they would be major characters. Also, Laura Ingalls could be a main character from the Little House side. She's a strong - willed and adventurous girl in the original story, so she could easily fit into a story with the Rangers.
One idea is that a character from the Little House, like Laura Ingalls, discovers a strange device that links her world to the world of the Power Rangers RPM. She then teams up with the Rangers to stop an evil force that is starting to corrupt both of their worlds. The Rangers could teach her some of their combat skills, and she could show them how to survive in the more rustic environment of the Little House world.
I really like fanfictions about Power Rangers RPM. 'A Single Moment' might be about a crucial time in the story. It could be a moment of decision for one of the Rangers, like when they have to choose between saving a teammate or achieving a mission goal.
It could be a moment of great heroism. One of the Power Rangers might perform an amazing feat in that single moment, like single - handedly taking on a horde of enemies to buy time for the others.
One idea could be that the OC is a new recruit in the Power Rangers RPM team. Scott initially doubts the OC's abilities, but as they face challenges together, he realizes the OC has unique skills and they form a strong bond. For example, in a battle against a powerful enemy, the OC uses their unorthodox fighting style to turn the tide, and Scott starts to respect them more.
Well, it depends on your taste. If you like crossovers between different fictional universes, it might be interesting. But some people might not be into the idea of mixing 'Little House' with 'Power Rangers'.
A great fanfiction idea could be that the OC has a special power that is linked to nature. Scott is initially skeptical about this power, thinking it's too unruly. However, when the team is facing a new type of enemy that is causing environmental disasters, the OC's power becomes crucial. They work together to figure out how to use the power to stop the enemy. As they do this, they develop a deep emotional connection, with Scott realizing the value of the OC's unique abilities.
It could be Dan Kuso from Bakugan as one of the main characters. He could bring his Bakugan expertise to the Power Rangers' team. And of course, the Red Power Ranger could be a main character too, leading the combined efforts of the Bakugan and Rangers.
A third creative storyline could be a time - travel crossover within the Power Rangers RPM universe itself. The Rangers could travel back in time to a point before the main events of RPM. They could meet their past selves or the predecessors of their technology. This would be a great opportunity for character development. They could see how far they've come and also learn from their past mistakes. Maybe they find out that a decision made in the past was what led to the current big threat in their present time, and they have to figure out a way to change it without disrupting the entire timeline.
One idea could be creating an OC who is a mechanic with a hidden power. They could be the one to upgrade the Power Rangers' Zords in unique ways. Another idea is an OC from a different dimension who comes to help the RPM Rangers fight the villains. They might have powers that the RPM team has never seen before.
In a Harry Potter - Power Rangers crossover fanfiction, the main characters could be Ron Weasley from Harry Potter and the Pink Ranger from Power Rangers. Ron could provide some comic relief as well as his loyalty and friendship skills. The Pink Ranger could bring her unique combat style and femininity to the story. And of course, Dumbledore could play a major role too. His wisdom and power would be a great asset in dealing with the combined threats from both universes.