One idea could be a crossover where the characters from Danny Phantom and LoliRock team up to fight a common supernatural threat. Maybe the ghosts from Danny's world are being influenced by a dark magic from the LoliRock universe, and they have to combine their powers to stop it.
Another idea is a story where Danny somehow gets transported to the world of LoliRock. He could be initially confused but then realizes he can use his ghost powers in new and unexpected ways in this magical world. The LoliRock girls could be both intrigued and a bit wary of him at first.
Another idea is a story about Danny and Star accidentally swapping powers. Danny has to deal with Star's magic while Star tries to control Danny's ghost abilities. It could be a comical yet challenging situation for both of them as they learn to adapt.
One idea could be that Danny gets an illness that affects his ghost powers. For example, he might start losing control over his intangibility or invisibility. This could lead to some really comical or dangerous situations. Another idea is that his friends try to find a cure for his strange ghost - related illness while also keeping it a secret from the town.
One idea could be a crossover where Naruto characters are transported to the Lolirock universe. They could team up with the Lolirock girls to fight a common enemy. For example, Naruto's skills in combat and his ability to use chakra could be combined with the magical powers of the Lolirock girls for a really cool battle sequence.
One idea could be exploring Danny's relationships in a different way. For example, how his friendship with Sam and Tucker might develop if they faced a new supernatural threat. Another could be a story where Danny discovers a new power and has to learn to control it while dealing with school and his ghost - fighting duties. And perhaps a fanfiction where Danny travels to an alternate dimension within the Danny Phantom universe.
A possible plot could be that there is a ghostly music competition in the Ghost Zone. Danny enters to stop some sort of dark plot related to it, and Ember is also a participant. Along the way, they form an alliance and their relationship blossoms as they work together to uncover the mystery behind the competition.
One idea could be that Danny somehow gets transported to the Digital World. He uses his ghost powers in unique ways to survive and help the Digimon. For example, his intangibility might be useful against certain digital threats that the Digimon can't deal with on their own.
One idea could be that Skulker, instead of always hunting Danny, teams up with him to face a new and powerful ghost threat that is endangering the entire Ghost Zone. This would force them to put aside their differences and use their unique skills together.
One idea could be that Danny's ghost powers are misinterpreted by Batman as some new kind of meta - human ability. Danny might end up being hunted by Batman at first until they realize they can work together to fight a common enemy like a powerful ghost that has escaped into Gotham.
Maybe there's a rift in the multiverse that connects the two worlds. Integra discovers Danny's powers and tries to recruit him to help in the fight against the vampires. Danny, being a hero in his own world, is hesitant at first but realizes the importance of cooperation when he sees the scale of the vampire threat in the Hellsing universe. He could use his intangibility and flight to outmaneuver the vampires while Alucard and Seras provide the heavy - hitting attacks.
Maybe Pandora has a powerful artifact that could help Danny in his fight against a particularly strong and evil ghost in his own world. Danny travels to Pandora to retrieve it, but he has to face many challenges there. The different ecosystems and magic on Pandora make it difficult for him to navigate, but he also meets some friendly creatures who help him along the way.