Maybe Gohan is summoned to the Sekirei world for some unknown reason. He then befriends some of the Sekirei and starts to train them in martial arts. This would not only help the Sekirei in their battles but also change their perspective on strength. Gohan's kind heart and strong sense of justice would lead him to oppose the Ashikabi system if he finds it unjust, and he'd try to find a new way for the Sekirei to coexist peacefully.
It depends on how you define 'powerful'. In terms of pure physical strength and combat ability, Gohan would be at the top. However, if we consider the Sekirei's special abilities like their unique powers related to their numbers and the ability to form bonds with Ashikabi, they have their own advantages. But overall, Gohan's Super Saiyan powers and his training with the Z - Fighters would make him the most powerful in a direct confrontation.
One possible plot could be that the Straw Hat crew sails to the world of Sekirei. Luffy might be intrigued by the concept of Sekirei battles and try to participate in a friendly way. Maybe Zoro would find some Sekirei with interesting sword - fighting skills and have duels with them. And Nami could be interested in the economic aspects of the Sekirei world, like how they trade resources or manage their finances.
A possible plot could be that Ichigo is transported to the Sekirei world during a battle with a powerful Hollow. There, he meets a Sekirei who has the ability to sense spiritual energy like he does. They form an alliance to stop a common enemy that is threatening both the Sekirei and the humans in that world. This enemy could be a rogue group of Sekirei who want to take over the world by any means necessary. Ichigo's unique powers and his experience in fighting powerful foes would be crucial in this scenario.
Well, perhaps the Sekirei start to appear in Hogwarts. Some students might accidentally bond with them. Harry could be in a dilemma as he tries to balance the chaos this causes in the school with the need to keep the wizarding world safe from external threats like Voldemort. The Sekirei's abilities could add a new dimension to the magical battles in the Harry Potter universe.
A Sekirei and One Piece crossover would be cool too. Picture the Sekirei on the Grand Line. Their unique abilities would be a great addition to the already diverse world of pirates. They could join pirate crews as new members or cause chaos as they search for their Ashikabi among the pirates.
Well, it could be about Shirou getting involved in the Sekirei battles. Maybe he uses his skills from his original story to help or compete in the Sekirei world. For example, his sword - fighting abilities might give him an edge in combat against other Sekirei or their Ashikabi.
One idea could be a crossover with the Dragon Ball Super universe. Future Gohan could meet the present - day Goku and Vegeta. They could train together and learn new techniques from each other. Another plot could involve a crossover with the Naruto universe. Gohan might use his ki powers in the ninja world, and perhaps have to face off against powerful ninja like Naruto or Sasuke. He could also learn some ninja skills in return.
A third idea is a crossover with the DC universe. Gohan could team up with Superman. Their combined strength would be off - the - charts. They could face off against powerful villains like Darkseid. Gohan's Saiyan fighting instincts combined with Superman's moral compass would make for an interesting dynamic, and they'd surely learn a lot from each other.
For a 'dbz gohan crossover fanfiction', a plot where Gohan crosses into the DC Comics universe would be exciting. He could team up with Superman and learn about different types of powers. Maybe he'd help Superman understand the concept of ki. Another idea is a crossover with the Final Fantasy series. Gohan could find himself in a world full of summons and magic, and use his martial arts to fight alongside the Final Fantasy characters.
A crossover with the Naruto universe is also a possibility. Godlike Gohan could end up in the Hidden Leaf Village. His power would be a mystery to the ninja there. He could help Naruto and the others fight against a new threat, perhaps an ancient evil that was sealed away long ago but has now been released. His energy attacks would be different from the ninja jutsu, and he could teach the ninja some new ways of fighting.