One way to start writing a Shantae crossover fanfic is to focus on the characters' relationships. If you're crossing her over with, say, Link from Zelda, think about how they would interact. Are they friends right away? Do they start as rivals? Build on these relationship dynamics. Also, think about the setting. Will it be mostly in Shantae's world, the other character's world, or a new hybrid world? Sketch out some key scenes that show the crossover elements clearly. Don't be afraid to experiment with different writing styles to make the story stand out.
First, decide which other universe or character you want to cross Shantae over with. It could be a character from a game you love or a whole new fictional world. Then, think about the plot. What's the main conflict? Maybe it's a new villain that only they can defeat together. Next, consider how the two different worlds' rules and magic systems will interact. For example, if it's a crossover with a sci - fi world, how will Shantae's magic work there? Start with a simple outline of the beginning, middle, and end of the story.