One idea could be to have Naruto find the Ocarina of Time in the Hidden Leaf Village. Maybe it was left there by a wandering traveler from the 'Ocarina of Time' world. Naruto, being curious, starts to play it and unknowingly opens a portal to the world of 'Ocarina of Time'. He then has to navigate this new world, using his ninja skills and making new friends and allies there.
A third fanfiction concept could be a shared enemy. Suppose an evil force from the 'Ocarina of Time' world, like Ganondorf, discovers a way to enter the Naruto world to seek more power. Naruto and his friends, along with characters from 'Ocarina of Time' like Zelda and Link, have to team up to defeat this common foe. They would have to combine their unique abilities, such as Naruto's Rasengan and Link's swordsmanship, to stand a chance against the powerful enemy.
A great plot for 'ocarina of time crossover fanfiction' could be a crossover with the Final Fantasy series. Link could meet characters like Cloud or Squall. They could exchange combat techniques and magical abilities. For example, Link could learn some of the complex spellcasting from the Final Fantasy mages, while the Final Fantasy characters could be intrigued by Link's use of the Ocarina. Or perhaps a crossover with the Pokémon world. Link could befriend Pokémon and use them in his quests, while also teaching the Pokémon trainers about the ways of Hyrule.
To write a great 'Naruto' and 'Ocarina of Time' fanfiction, you should also consider adding your own unique twists. Maybe there's a special power that comes from combining chakra and the magic of the Ocarina. Or perhaps there's a prophecy in both worlds that foretells the coming of the crossover. This will make your fanfiction stand out from others and attract more readers who are looking for something fresh and exciting in this crossover concept.
One unique idea is exploring the dark side of the Triforce. In some fanfictions, after Ocarina of Time, the power of the Triforce is misused or has unforeseen consequences. Also, there are fanfictions that focus on the Sheikah tribe's role in the post - Ocarina of Time world. They were important in the game, and these fanfictions expand on their influence, like how they might be involved in protecting ancient secrets that could change the future of Hyrule.
A great idea for zelda ocarina of time fanfiction is to imagine an alternate ending. What if Link failed to defeat Ganon? How would the world be different? You could also write about Link training with the different sages before facing Ganon, showing his growth in power and knowledge. Additionally, a story about the origin of the Master Sword and its connection to the Ocarina could be very interesting.
Good characters to include in 'ocarina of time crossover fanfiction' when crossing over with the Dragon Ball series could be Goku. His superhuman strength and love for fighting would make for some exciting battles with Link. Vegeta could also be there, adding his prideful and competitive nature. And from the Sonic the Hedgehog series, Sonic himself would be a great addition. His speed and cocky attitude would be a fun contrast to Link's more reserved demeanor.
One idea could be exploring Link's time in Kokiri Forest before he sets out on his adventure. Maybe show his relationships with the other Kokiri in more detail. Another could be a story where Zelda has to take on a more active combat role instead of just being the damsel in distress. And a third idea might be a fanfiction that delves into the backstory of the Ocarina itself, like who made it and what secrets it holds beyond what we see in the game.
The ocarina could make Naruto more introspective. Usually, he's all about action and fighting for his friends. But with the ocarina, he might start to look inward more. For example, as he plays, he could think about his own emotions and how they've been affected by all the events in his life.
Another concept is that a common enemy forces Naruto and Hellboy to team up. This enemy could be a powerful being that has the ability to disrupt both the ninja world and Hellboy's world. Naruto's jutsu and Hellboy's brute strength and Right Hand of Doom could be combined in creative ways to fight this foe.
Another possibility is that a villain in the Naruto world tries to use Nunnaly for her unique knowledge or skills. The shinobi of the Hidden Leaf, including Naruto, would then have to protect her. In the process, Nunnaly could learn about the values of the shinobi world like loyalty and perseverance.
One idea could be that Ichigo and Naruto are brought together by some sort of interdimensional rift. They initially don't understand each other's powers but soon realize they share a common goal of protecting their friends and worlds. They could team up to fight a powerful enemy that threatens both their universes.