Perhaps in the fanfiction, the Triforce from Zelda somehow ends up in the Mushroom Kingdom. This causes a great disturbance as various characters in Mario's world start to be affected by its power. Link arrives in the Mushroom Kingdom to retrieve it, and Mario helps him. They face challenges like Bowser trying to use the Triforce for his own evil purposes, and they have to work together to stop him and return the Triforce to its rightful place in Hyrule.
One idea could be that Mario and Link team up to save both the Mushroom Kingdom and Hyrule from a common enemy. Maybe a powerful dark wizard has found a way to merge the two worlds in a chaotic way, and they have to use their unique skills to restore order. Mario's jumping and power - ups combined with Link's swordsmanship and item - using abilities would make for an exciting adventure.
One idea could be that Naruto and Link swap worlds. Naruto finds himself in Hyrule and has to figure out how to use the Master Sword while Link ends up in the Ninja world and tries to learn chakra control and ninjutsu. Another idea is a combined quest where characters from both universes team up to defeat a common enemy, like a powerful dark sorcerer who is causing chaos in both the Elemental Nations and Hyrule.
Well, a cool plot for Mario Sonic crossover fanfiction might involve a new character that can travel between their worlds freely and is causing chaos. Mario and Sonic initially suspect each other but then realize they need to join forces. For example, this character could be stealing power - ups from Mario's world and Chaos Emeralds from Sonic's world to gain ultimate power. They would have to explore both worlds, facing their respective villains' minions along the way.
One idea could be that Mario and Luigi get transported to a strange new world where the rules of their own world are all mixed up. They have to use their combined skills in a whole new way to find their way back home. For example, Luigi might have to be more brave and take the lead in some situations while Mario has to use his speed in different ways than he's used to.
One idea could be that Mario and Sonic have to team up to save both their worlds from a new, powerful villain that is threatening to merge their dimensions in a chaotic way. For example, Bowser and Dr. Eggman could accidentally awaken an ancient evil while arguing over who is the better baddie.
Another concept could be that some of the magical creatures from Harry Potter end up in the Zelda world. Hippogriffs could be used as a form of transportation for Link and his allies. And the house - elves could have an interesting role, perhaps they help out in the various villages in the Zelda world, using their magic to clean up and cook, while also getting a taste of freedom in this new world.
One idea could be Link crossing over into a modern world. He'd be confused by the technology like cars and cell phones. Another could be Link teaming up with a character from another game, like Mario. They could combine their skills to defeat a common enemy.
One idea could be a crossover with the Final Fantasy series. Link could meet characters like Cloud and they could team up to fight a new, powerful enemy that threatens both their worlds. Maybe the magic systems of both universes get combined in an unexpected way.
Some great Legend of Zelda crossover fanfiction concepts include a crossover with the Sonic the Hedgehog series. Link could be racing through the Green Hills Zone on Epona. A crossover with the Super Mario Bros. universe is also a fun idea. Link and Mario could join forces to rescue Princess Zelda and Princess Peach from the clutches of their respective villains. Additionally, a crossover with the Kingdom Hearts series would be epic. Link could interact with Sora and the other Keyblade wielders, exploring different Disney and Zelda worlds together.
Maybe Zelda herself could be transported to the Avengers universe. With her wisdom and magic, she could assist the Avengers in different ways. She could use her magic to heal the wounded Avengers or help Tony Stark understand some ancient technology that has similarities to her own world's tech. She could also provide strategic advice based on her experience dealing with Ganon in her own realm.
One idea could be that Link, from Legend of Zelda, somehow gets transported to the Naruto universe. He might initially be mistaken for a strange shinobi with his unique green tunic and hat. Link could use his combat skills, like swordsmanship and shield defense, to team up with Naruto and his friends against common enemies, such as the Akatsuki who are after powerful artifacts. Maybe the Ocarina of Time has some sort of power that the Akatsuki wants, and Link has to protect it while in this new world.