In a Danny Phantom and Justice League crossover fanfic, Danny could team up with Superman. Maybe Danny uses his ghost powers to help Superman when he's facing a powerful ghost - like enemy that the Justice League can't handle with their normal tactics. It would be a really cool combination of the two universes.
In such a crossover, Danny could team up with Superman. Danny's ghost powers would be really interesting combined with Superman's super strength. Maybe they'd fight a common enemy that has powers related to both the supernatural and advanced technology.
I think it could be Superman. Superman is all about truth and justice and he would likely see the good in Danny. Also, they both have super strength in a way. Danny has his ghostly strength and Superman has his Kryptonian strength. They could bond over protecting the innocent.
I think Danny and Batman would have really interesting interactions. Batman is always cautious and calculating, and Danny's half - ghost nature and his more carefree attitude would create a great contrast. Batman would probably try to study Danny and his powers, while Danny would be both impressed and a little intimidated by Batman's detective skills.
Danny could use his ghostly powers to disrupt the technology that some Justice League members rely on. For example, he could mess with Cyborg's systems. His ability to overshadow people might also be a key factor, allowing him to control some of the less - powerful members.
I'm not entirely sure as I haven't read this specific fanfiction. It could be about a disrupted or alternative version of a story where Danny Phantom interacts with the Justice League in some unexpected or 'broken' way.
One common theme is the clash of two different worlds. Danny comes from a world where ghosts are a big part of his life, and the Justice League is from a more traditional superhero world. So there's often a theme of how they deal with each other's differences.
I think Danny and Batman would be a really interesting pairing. Batman is all about strategy and detective work, and Danny with his ghost powers could provide a different kind of assistance. Danny might be able to use his intangibility to access places Batman couldn't, and Batman could help Danny with his combat skills and planning.
Maybe there's a villain who has the ability to cross between the dimensions of Danny's world and the Young Justice world. Danny and the Young Justice team have to combine their efforts to stop this villain. Danny could teach them about dealing with supernatural threats, while they could show him how to work better in a team setting in a more traditional superhero sense.
I think Superman would be the most likely. Superman is known for his kind heart and open - mindedness. He would probably see Danny as a young hero in need of some guidance and friendship. He wouldn't be too quick to judge Danny based on his ghostly appearance or powers.