The fanfiction would likely involve Goku enrolling in the high school in the DxD world. His godlike abilities would make him a target for some and an idol for others. He could team up with the main characters to face common enemies. Goku would probably find the whole concept of Sacred Gears fascinating and might even try to figure out a way to use ki to power them up. His presence would also bring a sense of humor as he misunderstands some of the cultural and social norms in the DxD world.
Well, it would be wild. Goku could use his Instant Transmission to surprise everyone in Highschool DxD. His Super Saiyan forms would be like nothing they've ever seen. He might even participate in the Rating Games, and with his strength, he'd be unbeatable. His ki attacks would be mistaken for some kind of new magic or sacred gear power. And his simple - minded but kind - hearted nature could lead to some interesting interactions with the more complex characters in DxD.
It could be a really exciting story. Goku's godlike powers in the world of Highschool DxD would surely disrupt the power balance. He might introduce new fighting styles and values to the characters in DxD. For example, his Saiyan pride and never - give - up attitude could inspire the devils, angels, and fallen angels in that universe. Maybe he'd end up being a mentor figure to Issei or other main characters, teaching them how to reach new levels of power through training and self - discovery.
One idea could be that Naruto, with his godlike powers, somehow ends up in the world of Highschool DxD. He meets Lucifer and they initially have a clash due to misunderstandings. Naruto's power might surprise Lucifer and his followers. As the story progresses, they could find common ground and team up against a greater threat that endangers both Naruto's world and the Highschool DxD universe.
Goku would fit in as a super - powerful outsider. His physical strength and combat skills are far beyond what the normal characters in Highschool DxD are used to. He could become a sort of protector for the school, using his powers to fend off any threats that come their way. His energy - sensing ability would give him an edge in detecting hidden enemies.
One idea could be a crossover where the protagonist from DarkSiders ends up in the world of Highschool DxD. Maybe he has to navigate the complex social and supernatural hierarchies there while also trying to find a way back to his own world. He could bring his unique combat skills and abilities from DarkSiders and use them in the battles that often break out in the Highschool DxD universe.
One idea could be a crossover where Naruto characters are transported to the world of The Highschool of DxD. For example, Naruto himself could end up at the high school and his ninja skills would be quite a shock to the devils and other beings there. He might get involved in the Rating Games, using his shadow clones and other jutsu to his advantage.
One idea could be that Ben Tennyson somehow ends up in the world of Highschool DxD. Maybe his Omnitrix gets a strange power-up that transports him there. He could use his alien forms to interact with the characters in DxD, like using Four Arms in a fight against some of the devils or fallen angels.
A more complex fanfiction could be about a joint mission between the two universes. The leaders of both worlds realize that there is a common threat that only the combined forces of Highschool DxD and Naruto can defeat. So, they send their best characters, like Rias and Sasuke, to work together. This would involve a lot of character development as they learn about each other's cultures and powers.
A story could also revolve around a quest that involves both Diablo and Highschool DxD elements. The characters from both universes could team up to find a powerful artifact that has significance in both worlds. They would need to overcome their differences and work together, with the devils and angels from Highschool DxD learning about the dark and dangerous forces from Diablo.
One possible scenario in this fanfiction could be Naruto having his unique ninja skills in the Highschool DxD world. His godlike abilities might make him stand out among the devils and other supernatural beings. He could use his shadow clone jutsu for various strategic purposes, like infiltrating devil strongholds or getting out of tricky situations during the school's chaotic events.
A fanfiction could focus on Ichigo attending the school in Highschool DxD. His presence would surely disrupt the normal balance. He might not be interested in the whole 'devil' and 'angel' thing at first, but gradually get involved. He could also introduce some of his Soul Reaper training methods to the students there, which would be very different from what they're used to.
Yes, there are some great ones. You can start by looking on fanfiction websites like FanFiction.net or Archive of Our Own. Just search for 'Goku Highschool DxD' and you'll find a variety of stories with different plotlines and interpretations.