It could be really exciting. Imagine Luffy meeting Superman. Luffy's rubber powers against Superman's super strength would be a sight to see. Maybe they'd start off as rivals, not understanding each other's ways at first, but then realize they both fight for justice in their own worlds.
In a crossover, there could be a lot of cultural exchange. The heroes of the Justice League, coming from a more modern and technological world, would be introduced to the swashbuckling, adventure - filled world of One Piece. The One Piece characters, on the other hand, would be exposed to different concepts of heroism. For example, Superman's selfless acts of saving the world would be something the Straw Hats could look up to. At the same time, the Justice League might be impressed by the loyalty and friendship within the Straw Hat crew, which is a strong value in the One Piece universe.
In a One Piece - Justice League fanfiction, perhaps Zoro could cross paths with Batman. Zoro's swordsmanship and his sense of justice might align with Batman's detective skills and his own brand of justice. They could exchange combat techniques and strategies, and Zoro could learn a thing or two about stealth from Batman.
They might be really confused at first. The world of One Piece is so different from their own universe. The concepts like Devil Fruits and the Grand Line would seem very strange to them.
If we consider Sanji and The Flash. Sanji's fast - moving kicks combined with The Flash's super - speed could be a deadly combination. Sanji could use The Flash's speed to enhance his kicks, making them even more powerful and difficult to dodge. And they could also use their speed to rescue people in danger in an instant.
Superman may see the similarities in the heroism of the One Piece characters to his own. However, he'd also notice the differences in how they achieve their goals. He might think about how he could incorporate some of their fearless attitudes into his own battles back home. Batman would be very observant. He'd study the motives of the villains in the One Piece fanfiction and how the heroes counter them, and might even get some new ideas for dealing with Gotham's rogues.
One idea could be that Tsunade is brought to the Justice League's universe through some sort of magical portal mishap. She could use her medical ninjutsu skills to help treat injured Justice League members, like when Superman gets hurt by a kryptonite - based weapon. Her tough - as - nails attitude would also make for some interesting interactions with Batman, who might be intrigued by her no - nonsense approach.
In a fanfiction, the Ghost Rider could form an alliance with Batman. Batman would be intrigued by the supernatural element that Ghost Rider brings. They could team up to take on villains who are using magic or other dark forces. Ghost Rider's powers of hellfire and his unearthly strength would be a great asset to the Dark Knight's strategic mind.
In a strange turn of events, a portal opened up and Vegeta found himself in Gotham City, home of Batman. Vegeta was confused but ready for a fight. Batman, always cautious, observed Vegeta. Eventually, Batman convinced Vegeta that there was a greater threat that required their combined efforts. The Justice League, including Wonder Woman, Flash, and Aquaman, joined them. Vegeta was impressed by their diverse abilities. During the battle against a mind - controlling villain, Vegeta's brute strength and the Justice League's strategic planning worked in harmony. Vegeta learned about teamwork from the League, and they all respected his warrior spirit in the end.
Tsunade would have an interesting dynamic with Wonder Woman. They are both strong female characters. Wonder Woman would likely respect Tsunade's leadership skills and combat abilities. Tsunade, on the other hand, might be impressed by Wonder Woman's god - like powers.