One idea could be a character using the time - stop ability to save a teammate from a deadly attack. For example, Ruby could stop time to move Weiss out of the way of a Grimm's strike. Another could be a villain using it to set up a complex trap that the heroes have to figure out how to escape from once time starts again. Maybe they freeze time to manipulate the environment and make it more dangerous for the RWBY team.
Maybe in the fanfic, a villain has the stop - time ability. This causes chaos as they start stealing important artifacts while everyone else is frozen. The RWBY team has to find a way to counter this power, perhaps by teaming up with a time - wizard who teaches them how to move in stopped time.
One idea could be Ruby traveling back in time to the moment when Beacon Academy was first founded. She could then use her knowledge of future events to prevent certain disasters from occurring, like the Grimm attacks that would later plague the school. Another plot could involve Ruby going back to a time when her mother was alive and getting to know her, which would add a lot of emotional depth to the story. Maybe she could also change some events in her mother's life that would have a ripple effect on the present she came from.
One idea could be a new student arriving at the school with a mysterious power that no one has seen before. This could cause both excitement and suspicion among the other students.
One idea could be a mercenary who is hired by a mysterious client to steal an ancient relic from Beacon Academy. He has to navigate through the various defenses and teams of Huntsmen and Huntresses.
A plot could involve an esports competition where teams from different kingdoms in the RWBY universe compete. The story could explore how the RWBY team overcomes rivalries and strategic differences. They might also have to deal with a mysterious hacker trying to disrupt the tournament.
Well, you could have a story where all the RWBY characters swap their semblances for a day in chibi form. Ruby with Weiss's glyphs, Weiss with Blake's shadow clones, Blake with Yang's strength, and Yang with Ruby's speed. It would lead to some really funny and unexpected situations as they try to go about their normal activities at school. Or perhaps a fanfiction where the chibi RWBY teams are transported to a world made entirely of sweets. They have to resist the temptation to eat everything while also finding a way back home. A third option might be a mystery plot. A valuable item has gone missing in Beacon's chibi - version campus, and the teams have to solve the mystery of who took it and why.
One idea could be a new character arriving at the battlefield with a unique semblance that changes the tide of battle. For example, a character with the ability to manipulate time in a small area, allowing allies to get in extra attacks while enemies are frozen for a moment.
One idea could be Noctis arriving in the RWBY world and having to learn about Dust and how to use it in combat. Maybe he teams up with Team RWBY to fight against a new type of Grimm that his unique skills are well - suited to defeat.
A possible plot for 'rwby the incredibles fanfiction' is that Syndrome from The Incredibles teams up with Salem from RWBY. Syndrome offers his advanced technology to Salem in exchange for her help in getting revenge on the superhero community. The RWBY characters and the remaining Incredibles then have to find a way to stop this unholy alliance. They might start by training together to combine their different skills. Ruby could teach Dash some new acrobatic moves, and Elastigirl could show Blake how to use her flexibility in combat more effectively.
Another plot could involve a race between different teams in RWBY to claim a powerful battleship. This battleship could hold the key to some great power or knowledge. Along the way, they face various challenges and obstacles, both from each other and from external forces.