Well, here's an idea. There's a powerful cosmic entity that's siphoning energy from both the Dragon Ball universe and the Marvel universe. Goku and Captain Marvel sense this and are drawn to the source. Along the way, they meet various allies and enemies from both universes. They start to teach each other their unique combat techniques. Goku shows Captain Marvel the Kaioken and Spirit Bomb, while Captain Marvel teaches Goku about her energy projection and flight skills. As they get closer to the entity, they face tougher challenges and have to trust each other completely to stand a chance at defeating it.
A plot could involve Goku and Captain Marvel being on opposite sides of a moral dilemma. For example, Goku might be more focused on a pure battle for the sake of getting stronger, while Captain Marvel is more concerned with protecting the innocent. This conflict could lead to some intense battles between them at first, but then they discover a greater threat that makes them see eye - to - eye. Also, they could be in a story where they are both summoned to a strange new world and have to rely on each other to find a way back home. Maybe they find a powerful artifact there that has the power to change the balance of power in their respective universes.
One idea could be Captain Marvel bringing back some alien tech that the Avengers have to figure out how to use. It could lead to new powers for some of the members or a new way to defend Earth.
One idea could be that Naruto and Captain Marvel are brought together by a powerful cosmic force. They have to combine their unique abilities, Naruto's ninja skills and Captain Marvel's superpowers, to defeat a common enemy that threatens both their worlds. For example, a powerful alien race that is draining chakra from Naruto's world and energy from Captain Marvel's universe.
One idea could be a story where Captain America and Captain Marvel team up to face a new cosmic threat that's headed towards Earth. They have to combine their unique skills, with Captain America's strategic mind and combat experience on the ground, and Captain Marvel's incredible cosmic powers in space battles.
One idea could be that Captain Marvel and Spider - Man team up to stop a powerful alien threat that's immune to most of Earth's defenses. They'd have to combine their unique powers. Captain Marvel's energy - based attacks and flight, along with Spider - Man's agility and web - slinging skills, would make for an exciting battle.
A crossover with Doctor Strange could be really cool. Maybe they have to deal with a magical threat that is spreading across different dimensions. Captain Marvel's strength and Doctor Strange's magic would create an interesting dynamic as they try to figure out how to stop it.
A plot could be about an alternate universe where Captain Marvel is initially distrusted by the Avengers. She has to prove herself and in the process, they all learn more about each other's powers and pasts. This could lead to some great character development and new alliances within the team.
One idea could be that Naruto and Captain Marvel are brought together by some sort of interdimensional rift. They have to figure out how to get back to their respective worlds while also dealing with threats in the new world they are in. Maybe they have to combine their powers, like Naruto's shadow clones and Captain Marvel's energy blasts, to defeat a powerful villain.
Imagine a fanfiction where Captain Marvel uses her energy - based powers in a completely new way during the final battle in Avengers: Endgame. Instead of just punching and flying around, she could manipulate the energy fields in a way that disrupts Thanos's entire army. This would be a creative take on her character and her abilities.
In some versions, the female Goku could be part of a prophecy. The two Gokus meet, and at first, there is some confusion and misunderstanding. But as they get to know each other, they discover that they are key to fulfilling the prophecy. They combine their powers and defeat an ancient evil that was threatening both of their worlds.
One idea could be that Goku and Goku Black are forced to team up against an even greater threat from another universe. They start to understand each other's fighting styles during the battle and gradually develop a grudging respect for one another.