You should start with research. Read a lot of existing fanfiction to get an idea of what works and what doesn't. When it comes to actually writing, start small. Write a short scene where two characters from different universes meet for the first time. Build on that, adding more elements of the crossover as you go. Don't be afraid to take risks and be creative with your ideas, but also make sure it stays true to the essence of both the MGSV world and the other world you're crossing with.
To start a Kakuzu crossover fanfiction, you need to have a clear goal for the story. If it's a crossover with the DC universe, you could start with Kakuzu arriving in Gotham City. He might start causing chaos as he tries to amass wealth in this new, unfamiliar place. Think about how the existing characters in the DC universe, like Batman, would react to him. Build on these interactions, adding in elements of Kakuzu's backstory and motives to create a complex and engaging narrative.
First, you need to have a good understanding of the Asura lore. Know their culture, powers, and how they interact in their own universe. Then, choose the other universe you want to crossover with. Research that universe thoroughly as well. After that, think of an interesting plot point that could bring these two universes together. For example, a mysterious portal that connects the Asura world to the other.
First, decide which universe or character you want to cross Beerus with. This is crucial as it sets the tone and direction of your story. For example, if it's a crossover with the Naruto universe, think about how Beerus' powers would interact with ninjutsu. Then, create an interesting starting point. It could be Beerus accidentally landing in the Naruto world due to some sort of space - time rift.
You should also plan out the plot. Decide on a central conflict. It could be something like a common enemy that both sets of characters have to face. Maybe in a crossover with 'Zootopia', there's a villain who wants to disrupt both the human - like world of the descendants and the animal - centered Zootopia. Then, start writing an engaging introduction that hooks the reader right away.
Think about the themes you want to explore. In an Ultraman and Sailor Moon crossover, you might explore themes of heroism and friendship. You can start by writing a scene that shows the contrast between Ultraman's more serious, alien - fighting nature and Sailor Moon's more magical, girl - power approach. This contrast can drive the story forward and create interesting interactions between the characters.
First, choose the two universes you want to cross over. For example, if you pick Wizard101 and Narnia, research both well. Know the characters, settings, and magic systems of each. Then, think of a plot that brings the two together. It could be as simple as a portal opening between the two worlds.
Begin by brainstorming the setting. If it's a crossover with a fantasy world like Middle - earth, figure out how Mechagodzilla fits in. Will it be a mechanical monstrosity that the hobbits and elves are terrified of at first? Outline your story structure. Start with an interesting hook, like Mechagodzilla crashing into Middle - earth. Then build the conflict and resolution.
First, decide which other universe or story you want to cross Alita with. Then, think about how Alita's character traits, like her strength and determination, will interact with the new setting. You can start by writing a short scene that shows her arriving in the new world.
Begin by brainstorming ideas for the crossover. For a Gaster Crossover Fanfiction, say with the Doctor Who universe, think about how Gaster and the Doctor would interact. They are both very intelligent characters, but with different ways of approaching problems. You could start with a scene that sets the stage for the crossover, like Gaster detecting some strange time - space anomalies that lead him to cross paths with the Doctor. Then, develop your characters further. What would Gaster think of the TARDIS? How would the Doctor react to Gaster's strange experiments? Build your story from these initial ideas, adding conflict and resolution as you go along.
First, decide which other universe or concept you want to cross the Decepticons with. Then, think about how the Decepticons' personalities and abilities will interact with the new setting. For example, if it's a crossover with a fantasy world, how would their mechanical forms be perceived? After that, come up with a basic plot idea, like the Decepticons are after a powerful artifact in this new world.