Another interesting concept could be that a character in RWBY has the ability to communicate with Godzilla. This character could act as a mediator between the people of Remnant and Godzilla. They could convince Godzilla to help them in battles against Salem's forces, and in return, the people of Remnant would help Godzilla return to his own world. This would create a unique alliance dynamic within the story.
One idea could be that Godzilla arrives in the RWBY world due to a strange rift in dimensions. The Huntsmen and Huntresses initially see Godzilla as a huge threat and try to fight it. But then they discover that Godzilla is actually there to fight a common enemy, like a new type of Grimm that is immune to normal attacks but vulnerable to Godzilla's atomic breath.
Maybe in the fanfiction, Godzilla's presence starts to affect the Dust in the RWBY world. Since Dust is a source of power and has unique properties, the interaction between Godzilla's radiation and Dust could lead to some interesting plot twists. For example, some characters might gain new abilities or some areas could become dangerous due to unstable Dust reactions.
One idea could be that Godzilla arrives in the RWBY world due to a strange dimensional rift. The Huntsmen and Huntresses initially see it as a huge threat and try to fight it. But then they discover that Godzilla is actually there to fight a common enemy, like a new type of Grimm that is immune to normal attacks but vulnerable to Godzilla's atomic breath.
One idea could be Godzilla emerging in the world of RWBY and the Huntsmen and Huntresses having to figure out how to deal with it. Maybe they initially mistake it for a new type of Grimm.
One idea could be a Godzilla crossover with King Kong. They could start off as enemies but then have to team up to fight a common, greater threat like an alien invasion. This would bring in the classic monster -vs- monster dynamic at first and then shift to an alliance against a new foe.
How about a Godzilla crossover with the Avengers? Maybe in a world where the Avengers exist alongside the Kaiju. Godzilla could be seen as both a threat and an ally. Iron Man could try to study Godzilla's power source while Thor might see him as a kind of primordial force. Captain America would be the one trying to keep everyone in line and figure out how to co - exist with this giant monster.
One idea could be that Godzilla somehow ends up in Equestria. The ponies are initially terrified but then realize Godzilla is more interested in protecting the land from some new dark force that has emerged there. Maybe Godzilla's size and power are a mystery to the ponies at first, and Twilight Sparkle tries to study him to figure out how he got there.
A Godzilla and Evangelion crossover would be cool. Godzilla could be the ultimate Third Impact scenario that the Evangelion units have to face. It would be a battle of titanic proportions with the mechs trying to take down the giant lizard using their unique weapons and Godzilla's raw power overwhelming them at times.
One idea could be that Godzilla Earth teams up with a group of humans who have developed advanced technology to fight off an alien invasion. The humans initially fear Godzilla but soon realize they need his power.
One interesting idea could be a crossover of different timelines within RWBY. For example, characters from the past meet the current ones and have to deal with the differences in their worlds. Another could be a crossover of different teams in unexpected ways, like Team RWBY having to team up with a rival team to face a common enemy that is more powerful than any they've faced before. And sometimes, there are crossovers that involve alternate versions of the characters, where their personalities or abilities are slightly different, which can lead to very unique and engaging storylines.
A plot could involve a mad scientist in the RWBY world who tries to recreate the power of Godzilla using Dust. However, the experiment goes wrong and starts to attract the real Godzilla. The RWBY teams then have to deal with the chaos caused by the approaching Godzilla. They might think that Godzilla is there to destroy their world, but as they fight, they discover that Godzilla is actually attracted to the unstable energy that the mad scientist created, which is also a threat to the balance of their world. So, they have to find a way to work with Godzilla to neutralize the dangerous energy source.
A possible plot idea is that Godzilla is drawn to the Geo - Front in Evangelion. The reason could be the powerful energy sources there. The NERV organization is then forced to either work with Godzilla or find a way to get rid of it. They might study Godzilla's biology to see if they can use any of its abilities to enhance the Evas. Another plot could be that an Angel takes on the form of Godzilla to deceive the Eva pilots. This would make the pilots question their usual tactics when facing an 'Angel' as Godzilla has different strengths and weaknesses compared to the normal Angels. Also, a plot where Godzilla's presence causes a shift in the power dynamics between the different factions in Evangelion, like SEELE and NERV, could be really interesting.