Naruto's Rasengan could be used in a similar way as some of the physical attacks in One Piece. For example, it could be as powerful as Luffy's Gear attacks. Also, his ability to jump great heights and distances might be on par with some of the Zoan Devil Fruit users' enhanced physical abilities.
Another possibility is that the One Piece world has its own version of the Juubi. The poneglyphs could hold secrets about this powerful entity. A character like Robin, with her ability to read the poneglyphs, discovers information about the 'One Piece Juubi'. Then the story could follow how the different pirate crews react to this new threat or opportunity, and how they might interact with Naruto characters if they were to cross over.
The Juubi could be a sort of ancient and powerful force that exists in both worlds in a hidden way. Maybe it was the origin of some of the devil fruits in One Piece. In Naruto, it's a known and feared entity. In the fanfiction, it could be that the Juubi's power was split long ago, and some of it ended up in the One Piece world, which is why there are such strange and powerful abilities there.
Yes, there are likely some. The Naruto and One Piece universes are so vast that when combined with the concept of a godlike Juubi in fanfiction, it can create really interesting and unique stories. Some fanfictions might focus on a character having Juubi - like powers in the One Piece world, or Naruto characters interacting with One Piece characters in a scenario involving the Juubi. However, the quality can vary greatly depending on the writer.
You can start by looking on popular fanfiction websites such as FanFiction.net or Archive of Our Own (AO3). These platforms have a large collection of fanfictions from various fandoms, including Naruto and One Piece crossovers. Just use the search function and type in relevant keywords like 'godlike juubi naruto one piece' to see if there are any available stories.
One interesting storyline could be a character from Naruto who has the power of the Juubi getting transported to the One Piece world and ending up in a harem situation. For example, Naruto himself with the Juubi's power might land on an island in One Piece and attract a group of female characters due to his unique abilities and kind heart. They would then embark on adventures together, with Naruto's ninja skills and the Juubi - influenced powers being a new element in the One Piece universe.
One possible interesting plot combination could be that Naruto, with his Juubi powers, somehow gets transported to the One Piece world. He might team up with Luffy and his crew. Naruto could use his shadow clone jutsu to help in battles against the pirates or the Marines. His ability to sense chakra could also be used to detect hidden treasures or enemies with unique powers in the One Piece world.
One interesting 'juubi naruto x kushina fanfiction' could be 'Naruto's New Power'. In it, the relationship between Naruto and Kushina is explored in a unique way with the addition of the Juubi's power influence. It shows how Naruto's connection to his mother is strengthened and how they face new challenges together.
Yes, there might be. There are numerous fanfiction stories out there in the Naruto fandom, and with such an interesting concept as 'naruto is juubi x fem bijuu', it's quite possible that someone has written a story about it. You can check on popular fanfiction websites like FanFiction.net or Archive of Our Own (AO3).
There are some. However, the quality can vary greatly. Some might focus more on Naruto's rinnegan abilities in the One Piece world, while others might explore the relationships between the Naruto and One Piece characters in a more creative way. It really depends on what you're looking for in a fanfiction. If you like epic battles, look for ones that emphasize the combat capabilities of Naruto's rinnegan in the context of the One Piece universe.