The plot could be that Raven is in a dire situation in her world. She discovers an ancient spell that might be able to bring a powerful ally to her side. She decides to use it to summon Naruto. Once Naruto arrives, they face a powerful enemy that is threatening Raven's world. They combine their powers, Naruto's Rasengan and Raven's dark magic, to defeat the enemy.
Maybe Raven's world is being overrun by a horde of dark creatures. She realizes that she needs someone with Naruto's strength and determination. She summons him, and at first, they have a hard time understanding each other due to their different cultures and powers. But as they train together to face the oncoming threat, they start to respect and learn from each other. Eventually, they lead an army of Raven's allies and Naruto's summoned clones to victory.
Well, one possible plot could be that the servant Naruto summons is from a future time. This servant has knowledge of events that are yet to happen in the Naruto world. Naruto then has to use this knowledge wisely while also keeping the servant's origin a secret from others who might misuse it.
The plot could start with Shirou being in a desperate situation in his own world. He discovers an ancient spell or artifact that has the power to summon a powerful ally from another dimension, which turns out to be Naruto. Naruto then helps Shirou fight against the enemies that are threatening his world. Along the way, they face challenges that require both of their skills, like Naruto using his Rasengan against magical beasts and Shirou projecting shields to protect them from enemy attacks.
Well, in such a fanfiction, Naruto might learn unique skills from the summons. For example, he could learn stealth from a cat - like summon or brute strength tactics from a bear - like one.
The fanfiction might start with Ilya performing a summoning spell that she thought would bring something else, but instead, Naruto appears. Since Naruto is always eager to make friends and help others, he quickly bonds with Ilya. They could then embark on a journey to find a way to send Naruto back home. During this time, Naruto could teach Ilya about the importance of perseverance and believing in oneself, just like he learned in his own adventures in the Naruto world.
A possible plot could be that there is a disturbance in the balance of the Naruto world. The sages believe that only a being from another realm can help. Naruto is chosen to perform the summoning. He summons Mordred, and at first, they don't get along because of their different backgrounds. But as they learn more about each other and the true nature of the threat, they form an alliance. Mordred teaches Naruto some new combat techniques, and Naruto shows Mordred the value of friendship and loyalty in his world. Eventually, they defeat the enemy and Mordred may or may not decide to stay in the Naruto world depending on how their relationship has developed.
One possibility is that Naruto's connection with the summons would make him more in tune with nature. For example, if he was raised by toads, he might learn their unique jutsu faster and have a different approach to combat. He could also have a different view on friendship and loyalty as summons often have a strong bond with their summoners.
Well, if Naruto summons Saber, it could lead to some really interesting battles. Saber's combat skills and noble phantasms could be a great addition to Naruto's world. She might face off against powerful ninja like Sasuke or Pain. Maybe she could help Naruto in his fight against the Akatsuki. It would be a very different dynamic compared to the normal ninja battles in the Naruto universe.
Well, in such a fanfic, Sarada might summon the Hokages to seek their advice on how to deal with a powerful enemy threatening the village. For example, she could ask Hashirama about his experience in founding Konoha and how to protect it from the roots.
Well, Future Naruto might bring back some lost techniques. For example, if there were jutsu that were forgotten over time, he could reintroduce them. He could also have a different attitude towards the village, maybe more world - wise, and this could influence Minato's view on how to lead and protect the village.
Maybe Harry summons Manda because he believes Manda has knowledge about a hidden magical artifact. Manda then guides Harry through a series of challenges to find this artifact which could be the key to saving the wizarding world from a new dark threat.