One idea could be a crossover with the Transformers universe. Picture Jaegers and Transformers teaming up to fight a common enemy. Another could be a crossover with the Godzilla franchise, where the Jaegers have to deal with Godzilla while also facing their usual Kaiju threats. A third idea might be a crossover with the Star Wars universe, perhaps with Jaegers having some sort of technology exchange with the droids or the Jedi using their powers in the context of the Pacific Rim battles.
Well, a cool Pacific Rim crossover fanfiction could involve a crossover with the Power Rangers. The Rangers could join forces with the Jaeger pilots. They could combine their powers and fighting styles to take on an even more powerful Kaiju. Or how about a crossover with the Avengers? The superheroes could bring their unique abilities to the fight against the Kaiju in the Pacific Rim world. And then there's the idea of a crossover with the Men in Black. They could deal with the alien aspects of the Kaiju in a different way than the PPDC.
One idea could be that Godzilla emerges in the world of Pacific Rim during a Kaiju attack. The Jaegers initially see Godzilla as another threat but then realize he's actually fighting the same enemy. They could team up, with Godzilla's raw power and the Jaegers' advanced technology combining to defeat the Kaiju once and for all.
One idea could be that the Jaegers are equipped with Transformer technology. For example, their power cores could be replaced with energon, giving them new abilities. Another plot could involve the Transformers teaming up with the Jaeger pilots to fight a common enemy that threatens both Earth and Cybertron. Maybe a new breed of Kaiju that can also assimilate Transformer technology.
A crossover with the Godzilla universe. Maybe the Jaegers are called in to assist when Godzilla is facing an especially powerful and numerous Kaiju horde. The Jaegers' advanced weaponry and strategic capabilities could complement Godzilla's raw power in this scenario.
One idea could be that the RWBY characters are Jaeger pilots. Ruby could use her speed and Crescent Rose in the cockpit to fight Kaiju. Another is to have Grimm as a new type of threat in the Pacific Rim universe, and the teams have to adapt their fighting styles.
One idea could be an OC who is a brilliant but unorthodox engineer. They come up with new Jaeger designs that are initially scoffed at but prove crucial in a battle. For example, a Jaeger with the ability to split into multiple smaller units for more flexible combat.
One idea could be that the Avengers are called upon to help in the Pacific Rim universe when a Kaiju threat becomes too great for the Jaeger pilots alone. They could use their unique powers to assist in battles. For example, Thor could use his lightning to power up a Jaeger's weapons system. Another idea is that some of the Avengers become Jaeger pilots themselves. Iron Man could use his tech knowledge to upgrade the Jaeger technology. And Hulk could be a great asset in the physical combat against the Kaiju.
One possible plot could be that Naruto and his friends discover a way to enter the Pacific Rim universe. They could use their ninja skills to pilot the Jaegers in unique ways. For example, Naruto might use his shadow clone jutsu to operate different parts of the Jaeger simultaneously, giving it an edge in combat against the Kaiju.
In this crossover fanfiction, there could be a situation where a powerful Kaiju has some sort of ability that is affecting Godzilla's normal behavior. The Pacific Rim team has to figure out how to reverse this effect while also fighting off other Kaiju threats. They send in their most advanced Jaeger to try and communicate with Godzilla and form an alliance. Along the way, the pilots of the Jaeger learn about Godzilla's history and the ancient battles it has fought against similar threats.
The story could start with Naruto being mysteriously pulled into the Pacific Rim dimension. He would be initially confused but quickly adapt. His rasengan could be modified to be used as a powerful weapon against the Kaiju. The story could explore how his ninja values of loyalty and perseverance play out in the context of the high - stakes battles in the Pacific Rim world.
Perhaps a story where a baby Kaiju is accidentally transported to a different dimension. In this dimension, it's the only Kaiju, and it has to adapt to a completely new environment. Meanwhile, the humans in the Pacific Rim world are trying to find a way to bring it back, not knowing how it will have changed in this strange new place.