A possible plot could be that there is a powerful and ancient treasure in the Pirates of the Caribbean world that is somehow connected to the chakra system in Naruto's world. Naruto senses this and travels there to investigate. Along the way, he meets the various characters from the Pirates of the Caribbean franchise. He has to face off against the villains who also want the treasure for their own evil purposes. Naruto uses his ninja abilities to outwit and defeat them, and in the process, he discovers a new form of chakra or power that is unique to this combined world.
One interesting plot could be that Naruto, with his ability to use chakra and perform ninjutsu, somehow ends up in the world of Pirates of the Caribbean. He might team up with Jack Sparrow. Naruto's speed and strength could help them in their sea adventures and battles against the cursed pirates or sea monsters. For example, he could use his Rasengan to break through the defenses of some powerful pirate ships or fight off the kraken-like creatures with his shadow clone jutsu.
One of the most interesting pairings could be Kakashi and Barbossa. Kakashi's calm and collected nature, along with his vast array of ninja skills, would be an interesting match for Barbossa's greedy and cunning personality. They could be in a situation where they have to work together against a common enemy, like a powerful sea witch or a group of rogue ninjas who have found their way into the Pirates of the Caribbean world. And then there's Hinata and Anamaria. Hinata's shy yet strong character could befriend Anamaria, and they could have their own little adventures on the high seas, perhaps looking for a special kind of ninja - pirate treasure.
Another idea is that the Straw Hat Pirates from 'One Piece' (since it has some similarities to 'Pirates of the Caribbean' in terms of pirate themes) accidentally sail into the world of 'Naruto'. They team up with Naruto and his friends to face a common threat like an ancient sea monster that has been awakened by Orochimaru's experiments. This would be a really exciting crossover as the different abilities of the characters from both universes would interact in interesting ways.
There might be a fanfiction plot where Elizabeth Swann, instead of being a damsel in distress at times, becomes a powerful pirate captain in her own right. She could lead her own ship and crew, and have adventures that cross paths with Jack Sparrow's. For example, she might be on a quest to find a magical artifact that can control the seas and has to outwit other pirates and sea monsters to get it.
Here's another plot twist. The Fountain of Youth in the Pirates of the Caribbean world is actually a creation of a minor Greek god from the Percy Jackson world. This god was trying to create a new power source but lost control of it. Now, both the pirates and the demigods are after it for different reasons. The pirates want eternal youth, while the demigods want to stop it from causing chaos in both worlds.
One great 'Pirates of the Caribbean x Reader Fanfiction' is 'A Pirate's Heart'. It has a really engaging plot where the reader character gets caught up in the adventures of Jack Sparrow and his crew. The way the author describes the pirate world makes you feel like you're really there.
The plot often involves a search for treasure. Pirates sail the dangerous seas, face other pirates and sea monsters while trying to find hidden gold.
Hermione might play the role of a strategist. Pirates need good plans to raid other ships or to escape from dangerous situations. With her sharp mind, she could come up with elaborate strategies that would give the pirates an edge. For instance, she could plan a diversion to distract an enemy ship while their own ship sneaks up from behind.
Another plot could involve Elizabeth Swann time - traveling. She gets sent to a future version of the Caribbean where piracy has been completely eradicated. However, she discovers that without pirates, the balance of power in the region has been thrown off and there are new tyrannical forces at play. So, she has to find a way to bring back the spirit of piracy in a more civilized way to restore the balance. She uses her knowledge from the past and her wits to start a revolution of sorts.
One idea could be that the RWBY characters find themselves on a cursed ship similar to the ones in Pirates of the Caribbean. Ruby could be the fearless leader, using her scythe in sword - fights on the ship's deck. Weiss might be the one trying to figure out the magic or curses involved, with her knowledge of Glyphs. Blake could use her stealth skills to explore the ship and discover hidden secrets, and Yang would be the muscle, ready to take on any enemy pirates.
One idea could be a crossover with 'Peter Pan'. The pirates could sail to Neverland and have adventures with Peter, Tinker Bell and the Lost Boys. Maybe Captain Jack Sparrow would try to steal the fairy dust from Tinker Bell.