One idea could be a Moana crossover with Frozen. Moana could end up in Arendelle due to a magical storm. She teams up with Elsa and Anna to stop an approaching iceberg that is threatening both her island and Arendelle. Moana's skills in sailing and her connection with the ocean could be combined with Elsa's ice powers to find a solution.
One idea could be that Moana discovers a hidden part of the ocean that has a special connection to her ancestors. The ocean could lead her there, and she might find ancient artifacts or powers that help her protect the island in a new way.
Perhaps the male OC is a mysterious figure who appears to Moana in her dreams before she even sets out on her journey. He seems to know a great deal about the heart of Te Fiti and the approaching darkness. When they finally meet in person, he reveals that he has a connection to an ancient power that can either help or hinder Moana's mission, and she has to figure out how to work with him.
Imagine a fanfiction where Moana and the Little Mermaid embark on an adventure to a mysterious island in the middle of the ocean. This island is said to hold the key to a powerful magic that can heal any damage to the ocean. Moana would be excited to explore the island, while Ariel would be a bit more hesitant as she is used to the underwater world. But once they land, they discover that the island is full of strange and wonderful things. They meet creatures that are part - plant, part - animal, and they have to solve puzzles to get closer to the magic. Their different perspectives and skills would make this a thrilling and unique adventure.
It could be about Naruto somehow ending up in Moana's world. Maybe he uses his ninja skills to help Moana on her journey to save her island. For example, Naruto could use his shadow clone jutsu to do multiple tasks at once like helping to repair damaged parts of the island while Moana focuses on finding the heart of Te Fiti.
Another concept could be a crossover where some of Naruto's friends like Sasuke or Sakura also end up in Moana's world. They all form a team with Moana and her friends to fight against a dark force that is trying to take over the ocean and the land.
One idea could be that they go on adventures together to explore new islands. Maui could use his strength and Moana her navigation skills.
One idea could be a story about Moana's journey during her pregnancy. It could focus on how she still tries to maintain her connection with the ocean and her village. Maybe she teaches the children about the importance of nature even while she's expecting.
In this fanfic, Moana is on a new voyage and gets lost in a mysterious part of the ocean. She ends up near Ariel's territory. Ariel, who has always been interested in humans, approaches Moana. At first, Moana is a bit startled by a mermaid but soon realizes they share a common love for the ocean. They start to exchange knowledge. Ariel shows Moana some of the amazing underwater wonders she has never seen before, and Moana teaches Ariel about the stars that help her navigate. Together, they face a sea monster that is causing trouble in both their areas of the ocean.
In a Harry Potter - Moana crossover fanfiction, the magical creatures in the Harry Potter world could interact with the spirits in Moana's world. For instance, a Hippogriff could fly over Moana's island and be seen as a strange new creature. Or the Maui's fishhook could have some sort of magical connection with a powerful wand in the Harry Potter universe. The characters' personalities would also make for great combinations. Hermione's intelligence and Moana's determination could lead them to solve some big mystery together that involves both their worlds.
It could be really interesting. Maybe Harry Potter uses his magic to help Moana on her journey. For example, he could use a spell to calm the rough seas she sometimes faces. Or Hermione could use her vast knowledge to figure out some of the mysteries in Moana's world that even she doesn't understand yet.