He could gain the ability to use a sword more effectively. Cloud is a master swordsman, and Naruto, under his tutelage, might learn some amazing sword - fighting techniques. Also, Cloud has some superhuman strength and speed, and Naruto could potentially inherit or be trained to have similar enhanced physical abilities.
Naruto might gain the power of shikai and bankai. Shikai is the first release of a zanpakuto's power, and bankai is the ultimate form. Naruto, with his determination and strong will, would strive to master these forms. Shikai could give him new attacks and defenses, while bankai could make him an extremely powerful force. For example, his bankai could combine his ninjutsu skills with the zanpakuto's power in a unique and devastating way.
Naruto could gain the ability to manipulate light and darkness, which are often associated with Keyblades. This would be a huge change from his normal chakra - based abilities. He could also use the Keyblade to fly, giving him an advantage in both mobility and combat. Another new ability might be the power to heal, as some Keyblades have restorative properties.
Naruto might be able to create cloud - based illusions. Just as he can create shadow clones, with the power of Cloud sealed in him, he could project illusions made of clouds to deceive his opponents. These illusions could be large - scale and very realistic, confusing enemies about his true location and intentions.
A plot could involve a merging of the two worlds. Due to some mysterious magic or scientific experiment gone wrong, the Naruto and Final Fantasy VII worlds start to blend. Naruto and Cloud Strife are two of the few who are aware of what's going on. They have to work together to find a way to separate the worlds again. Along the journey, they encounter various characters from both universes. Naruto might meet Aerith and be fascinated by her healing abilities, while Cloud Strife could meet Kakashi and learn about his Sharingan. They face many challenges, including battles with enemies who have also been affected by the world - merging, and in the process, they develop a deep respect for each other.
One possible plot could be that Cloud Strife is somehow transported to the Naruto world. He might initially be seen as a threat, but then he teams up with Naruto to fight a common enemy, like a powerful new Akatsuki member who has powers that can only be countered with Cloud's unique abilities.
Well, it might be. In the world of fanfiction, the boundaries are very loose. Writers can take a character like Cloud Strife and place him in the Naruto setting. They can then explore how he would adapt to the different culture, powers, and challenges in the Naruto world. Maybe he could learn ninjutsu or fight alongside Naruto and his friends. There are so many possibilities when it comes to fan - created crossovers.
He could gain the ability to create large - scale wooden structures, like Hashirama did. For instance, he could build huge wooden golems to fight for him in battles.
Naruto could potentially gain the power of omnipotence. Since the Infinity Stones are extremely powerful in the Marvel universe, in the Naruto fanfiction, they could give Naruto abilities beyond imagination. He might be able to use the Stones together to rewrite the rules of the ninja world. For example, he could make chakra obsolete and introduce a new form of energy using the combined powers of the Stones. Also, he could use the Power Stone to boost the power of his Rasengan to an unimaginable level, capable of destroying entire mountains with a single throw.
He might gain enhanced chakra control. Since he has the Kyuubi's soul, he could have better access to the Kyuubi's chakra reserves and be able to manipulate it more precisely. Maybe he could also gain some of the Kyuubi's natural abilities like better senses, especially smell, which could help him in tracking enemies or finding things.
Another ability Naruto could gain is a deeper understanding of genjutsu. Shisui was very proficient in genjutsu, especially with his Sharingan. Naruto, being his brother, could have a natural aptitude for genjutsu. He could learn to break through stronger genjutsu more easily and also use more advanced genjutsu himself. This would be a significant change as Naruto was not originally known for his genjutsu skills, but with this new connection, he could become a more well - rounded ninja.