Maybe in this crossover, some Pokemon are accidentally sent to Danny's world. Danny has to protect the Pokemon from being captured by the Guys in White while also trying to find a way to send them back. Meanwhile, a certain Pokemon, like Gengar, forms a special bond with Danny because of their shared ghostly nature.
Perhaps an organization made up of both Pokemon world villains and some of Danny's foes. They could be working together to create a portal that would merge the two worlds in a way that benefits them. They would be the main antagonists as they cause all kinds of chaos, stealing both Pokemon and technology from both worlds to achieve their goals.
I like the idea of a Danny Phantom and Ben 10 crossover. Ben has the Omnitrix which gives him access to different alien forms, and Danny has his ghost powers. They could either be rivals at first, each thinking their powers are better, or they could quickly team up to face a threat that requires both their unique abilities. It would be a fun clash of two very different power - based universes.
One interesting Danny Phantom Pokemon fanfiction is 'Danny and the Pokemon World'. In this story, Danny somehow gets transported to the Pokemon world and has to figure out how to get back home while also dealing with the unique challenges of the Pokemon universe. It has some great action scenes where Danny uses his ghost powers in combination with Pokemon battles.
One idea could be that Danny, as a half - ghost, has to prove himself to the Ghost King. Maybe there's a tournament in the Ghost Zone where Danny enters to show his worth. This could lead to some epic battles and alliances with other ghosts.
One idea could be that Danny, with his ghost powers, ends up in the RWBY universe. He could team up with Team RWBY to fight off Grimm that are being influenced by some sort of ghostly energy. His intangibility and flight would be really useful in battles.
In a crossover, characters from the other franchise might betray Danny. For example, if it's a crossover with a show about vampires, a vampire character who seems friendly at first could betray Danny for his ghost powers. They might want to use his powers for their own dark purposes. Another likely candidate could be a character who is jealous of Danny's abilities. Maybe in a crossover with a superhero world, a sidekick who feels overshadowed by Danny's powers and popularity might be the one to betray him.
It's interesting because it allows for a lot of creativity. Writers can come up with all sorts of crossovers. They can create new Pokemon species that are related to the elements of Danny Phantom, like a Pokemon that can phase through walls like Danny. Or they can write about how Danny would train his Pokemon differently due to his own experiences. There are endless possibilities for unique storylines and character developments in Danny Phantom Pokemon fanfiction.
I think Danny Phantom crossover fanfictions can be really exciting. They bring together different universes and characters, creating unique and unexpected storylines. For example, a crossover with a superhero universe could lead to Danny teaming up with other heroes to fight a common enemy. It's a great way to explore new character dynamics and expand the Danny Phantom world.
A common theme is the struggle between good and evil within Danny. When he's in his evil form in crossovers, it often shows the fight to bring him back to the good side.