A third idea is a battle royale - style story. Characters from both universes are brought together in a tournament. The Z - fighters would have to face off against the devils and angels from Highschool DxD. It would be interesting to see how Goku's pure - heartedness would interact with the more complex moralities of the Highschool DxD characters.
Another idea is a fusion of the power systems. Maybe in the fanfiction, the Sacred Gears from Highschool DxD could be enhanced by the Dragon Balls. The Dragon Balls' wishes could be used to unlock new forms or powers in the Sacred Gears. This would create a whole new level of power - ups for the characters in Highschool DxD.
One idea could be to have the characters from Dragon Ball Z attend the school in Highschool DxD. For example, Goku could be a transfer student with his incredible power causing quite a stir among the devils, angels and fallen angels. He might be confused by the different social dynamics and the whole concept of the supernatural school setting.
One popular crossover is a story where the characters from Naruto and Highschool DxD team up against a common enemy inspired by Dragon Ball Z villains. They combine their unique powers like Naruto's ninjutsu, the devils' abilities in Highschool DxD, and maybe some ki - based attacks from Dragon Ball Z.
There's also 'Dragon Ball Z Meets Highschool DxD: A New Adventure'. This fanfiction explores how the characters from the two universes interact when they are suddenly thrust together. It delves into how the power levels from Dragon Ball Z compare to the abilities in Highschool DxD and has a lot of humorous moments as the characters from different backgrounds try to understand each other. It's quite long, so there's a lot to get into. The author does a great job of developing the story over time, introducing new plot twists and character developments that keep readers engaged. It's definitely a must - read for fans of both series.
You can try websites like FanFiction.net or Archive of Our Own. These platforms usually have a wide variety of fanfictions, including ones related to Dragon Ball Z and Highschool DxD. Just use their search functions to look for the specific fanfictions you're interested in.
One interesting crossover could be the power - up systems. In Dragon Ball Super, characters achieve new forms like Ultra Instinct. In Highschool DxD, Issei has his Boosted Gear. A fanfiction could explore what would happen if Issei somehow got access to the Saiyan power - up system or if a Saiyan character got ahold of the Boosted Gear. Maybe the Saiyan's natural battle instincts combined with the Boosted Gear's power would create an incredibly powerful being.
Well, for 'Ben 10 Dragon Ball Z fanfiction', a cool concept could be that Ben gets caught in a time - space rift that sends him to the Dragon Ball Z universe right when a new and powerful enemy is emerging. Ben has to quickly figure out how to use his Omnitrix in this new world while also trying to get back home. And perhaps some of the Dragon Ball characters are intrigued by the Omnitrix and want to study it, leading to some funny and interesting interactions.
Another interesting concept would be Shallot getting lost in a different dimension within the Dragon Ball Z universe. He would have to find his way back while encountering strange new races and powers, and along the way, he might learn some valuable lessons about himself and his abilities. This could lead to him coming back to his own world as a much stronger and wiser fighter.
Some ideas for Dragon Ball Z Gine fanfiction include a time - travel story. Gine could be brought to the present day by some time - traveling villain or device. Then she has to adapt to the new world while also using her Saiyan knowledge and skills to help the Z - fighters. Another idea is to focus on Gine's family. Write about her relationship with Bardock in more depth, or create a story about her extended family on Planet Vegeta that we haven't seen before. You could also do a story where Gine meets the other Saiyans who were resurrected, like Nappa and Raditz, and how she interacts with them.
One idea could be a fanfiction where Vegeta gets a completely new haircut as a part of a disguise during a mission on a new planet. Maybe he has to blend in with the locals who have a very unique and flamboyant hairstyle. Another could be about Goku getting his hair cut by Chi - Chi because she wants him to look more presentable for a family gathering, but then he discovers that his power level is affected in some strange way. And a third idea might be a story where Trunks experiments with different haircuts to impress a new love interest in his timeline.
A great fanfiction idea could be about the Dragon Balls being accidentally transported to the Naruto universe. This would cause chaos as various ninja clans try to get their hands on them for different reasons. Maybe Naruto himself would be the one to discover them first and he has to figure out how to use them or protect them from those with malicious intent. And of course, there could be some fun interactions between Naruto's friends and the Dragon Ball Z characters who come looking for the balls.