Another option is a crossover with Harry Potter. Picture Goku going to Hogwarts. He could be confused by all the magic but also use his martial arts skills to defend the school from dark wizards. His super speed would be a great advantage against the slow - moving spells of some of the villains.
A crossover with One Piece might also be cool. Imagine Luffy and Goku teaming up. Luffy's rubber abilities combined with Goku's super strength could make for some really fun and unique battle scenes. They could be on a quest to find a powerful treasure that has both the power of the One Piece world and the Dragon Balls.
One idea could be that Goku and Naruto meet during a universal tournament. Goku, being his usual self, is excited to fight strong opponents. Naruto, on the other hand, is intrigued by Goku's pure love for combat. They could team up against a powerful enemy from another dimension who threatens both their worlds.
One idea could be a crossover with other popular anime like Naruto. Picture Goku meeting Naruto and having a friendly sparring match. Another could be a crossover with the DC Universe, where Vegeta and Superman have a showdown to see who's stronger. Or perhaps a crossover with the Final Fantasy series, with the Dragon Ball characters in a world filled with magic and summons.
One idea could be that Naruto and Goku meet during a interdimensional rift. They decide to have a friendly spar, with Naruto using his shadow clones and Rasengan while Goku goes Super Saiyan. Another could be that the Akatsuki are after the Dragon Balls for some reason, and the Z - fighters team up with the ninja of Konoha to stop them.
One idea could be a crossover with the Naruto universe. Goku and Naruto could have an epic battle or team up against a common enemy. Another idea is a crossover with One Piece, where the Z - fighters join Luffy's crew for a while. Or perhaps a crossover with Harry Potter, where the Dragon Ball characters have to deal with magic in the wizarding world.
One idea could be to combine the power - up mechanics of Dragon Ball Z with the strategic battles of Fire Emblem. For example, characters in the fanfic could gain new abilities similar to Super Saiyan transformations during intense battles in the Fire Emblem - like battlefields. They could use these new powers to turn the tide of the fight against the enemy forces, which could be a mix of both Dragon Ball Z villains and Fire Emblem antagonists.
One idea could be a crossover with the Naruto universe. Imagine Goku meeting Naruto and them having a friendly sparring match. Another could be a crossover with the One Piece world, where the Z - fighters team up with the Straw Hat Pirates to take on a common enemy. And a crossover with the Harry Potter universe, with the Saiyans learning magic at Hogwarts.
One idea could be a battle between Goku and Superman. They could start off as rivals, each thinking their own planet needs more protection. As they fight, they gradually realize they have more in common than they thought, like their strong sense of justice. Then they team up to face a common enemy, like Darkseid and Frieza working together.
A crossover with the One Piece universe could also be cool. Imagine Luffy and Goku having a friendly competition to see who can defeat more enemies. The different power systems, like Devil Fruits and ki, would create interesting battles and interactions.
A great 'Dragon Ball Super Crossover Fanfiction' concept might involve a crossover with the Harry Potter world. The Saiyans could visit Hogwarts. Maybe Vegeta could be really intrigued by the magic there and try to learn some spells, while at the same time the wizards are in awe of the Saiyans' power. There could be a dark wizard who wants to use the Dragon Balls for his own evil purposes, and the Hogwarts students and the Z - fighters have to work together to stop him.
One idea could be exploring a new transformation for the characters. For example, a fusion between an unexpected pair of characters that results in a super powerful form. Another idea is to set the fanfic in an alternate universe where the Saiyans never lost their planet and see how that changes the story and power dynamics. You could also focus on a side character and give them a more in - depth backstory and a major role in saving the universe.