One possible plotline could be that Naruto discovers a hidden threat to Sandaime before anyone else. Maybe he stumbles upon a secret enemy's plan while on a mission. He then uses his unique skills, like his shadow clones, to outwit the enemy and save Sandaime at the last moment. For example, he could create a diversion with his clones while he sneaks up on the bad guys and disarms them.
Perhaps Artemis gets lost in a strange dimension that is similar to Naruto's world. Naruto discovers her there and has to protect her from the dangerous creatures in that dimension. He uses his skills and knowledge of the area to lead her to safety. Along the way, they might form an unlikely friendship or even more, depending on the nature of the fanfiction.
A possible plotline could be that Tayuya is captured by an evil organization, and Naruto goes on a solo mission to save her. He uses his stealth skills to infiltrate the enemy base.
Perhaps in the fanfiction, the Sandaime betrays Naruto by revealing his secrets to the wrong people. Like, he tells about Naruto's connection to the Nine - Tails in a way that endangers Naruto. It could be because the Sandaime is trying to protect the village at all costs, even if it means sacrificing Naruto's well - being and trust.
One challenge could be that the enemy is too powerful for Naruto to defeat on his own. He might have to quickly level up his skills or find allies to help him. For instance, he might need to convince some of the more reluctant ninja in the village to join him in the fight.
One possible plotline is that Harry is magically transported to the Naruto world and discovers Naruto is in danger from a new, powerful enemy. Harry then uses his magic to fight alongside Naruto and his friends, saving Naruto in the process.
In some fanfictions, Naruto could be facing a powerful enemy that he underestimated. Temari steps in and saves him. This event could then trigger a series of events where Naruto starts to study Temari's fighting style to improve his own skills. At the same time, the two of them could get involved in some political intrigue within the ninja villages, as Temari is from Suna and Naruto is from Konoha. Their relationship could be a key factor in the stability between the two villages.
One possible plotline could be that Naruto, with his powerful ninja skills, suddenly appears in the world where Rias is in trouble with Riser. He might use his shadow clone jutsu to distract Riser while he rescues Rias. Another could be that Naruto uses his rasengan to break through any barriers or attacks that Riser has set up to keep Rias captive. Maybe Naruto is summoned there by some sort of magic or a wish that Rias unknowingly made, and he then uses his chakra to overpower Riser and save Rias.
A plotline could involve Naruto finding a hidden power within the Uchiha clan that was overlooked. He uses this power to unite the clan and make them strong enough to resist any threats. Maybe this power is related to an ancient Uchiha technique that Naruto helps to rediscover. He then uses his charisma and leadership skills to convince the Uchiha to work with the village instead of against it.
Perhaps Medusa has some crucial information that Percy needs to save the world, and in order to get that information, he has to protect her from other threats. So he embarks on a journey to keep her safe.
It could be that a powerful sorcerer in the Avengers' world goes rogue and starts using dark magic. The Avengers don't know how to handle magic, so Harry is called in. He has to face this rogue sorcerer, using his own brand of light magic. Along the way, he might have some clashes with the Avengers' way of doing things, but in the end, they all work together and Harry manages to save the day by defeating the rogue sorcerer and restoring peace in the Avengers' world.