The fanfiction can also add a new dimension to the characters. Chopper's relationship with lemons can show different aspects of his personality. If he's really into studying the lemons, it can highlight his scientific curiosity. And it can create new dynamics within the Straw Hat crew as they interact with Chopper's lemon - related adventures.
Well, Naruto's chakra - based abilities would be quite unique in the One Piece world. His Rasengan, for instance, would be a powerful new type of attack that most characters in One Piece haven't seen. His ability to walk on walls and water using chakra would also give him an edge in many situations. He might also be able to use his chakra to sense things in a different way than the Haki users in One Piece, which could be a big advantage when exploring islands or looking for hidden treasures.
Considering Luffy's character development, he has always been against those who harm his friends and the innocent. Akainu has caused great harm, especially during the Marineford War. If Luffy continues to grow in strength, and if the story progresses in a way that pits them against each other again, there's a chance. But the Marines also have their own ways of protecting their top - ranked officers, so it's a complex situation.
A novel where the main character transmigrated to One Piece with a level 99 cosmic system could be called One Piece: The Universe Pirates. This was a story with pirates as the theme. After the main character transmigrated to the world of One Piece, he used the cosmic system to become a pirate.
She'd fit in as a unique addition. Her magical abilities would set her apart. She could use magic to enhance the crew's abilities. For example, give Luffy a temporary boost in strength with a spell.
In fanfiction, if Naruto was born in One Piece, he could bring a new style of fighting. His speed and agility from being a ninja would give him an edge in combat. He could run across the masts of pirate ships like he runs on trees. His Sage Mode could be related to some kind of ancient knowledge in the One Piece world. And his strong willpower would fit right in with the characters in One Piece who often have to face great challenges. He might even inspire some of the characters to be more selfless in their pursuit of their dreams.
Goku Black could be a powerful new threat. His ability to instantaneously move between spaces using his powers would be like a more advanced form of the Shanks' ability to appear suddenly. He could easily target the weak points of the various islands in the One Piece world.
If we think about it, in a One Piece - Naruto crossover fanfiction, Naruto and Hinata would bring a whole new dynamic. The One Piece world is full of wacky and powerful characters. Naruto's rasengan could be a super - powerful attack in this world, and Hinata's gentle fist could be a unique form of martial arts. They could join a pirate crew or form their own. Their love story could also be a side plot, with Naruto being a bit oblivious at first, like in the original Naruto story, and Hinata being the one who's more in tune with her feelings, but in the context of the One Piece adventures.