In such a fanfiction, Naruto might gain some extraordinary powers related to the phoenix. For example, he could have the ability to heal quickly like the phoenix's regenerative powers. He may also be able to use fire - based attacks that are far more powerful and unique compared to his regular jutsu.
In a fanfiction with Naruto having Frieza sealed in him, there would be a clash of cultures too. Naruto comes from a world of ninjas with honor and teamwork, while Frieza is a tyrant from a universe where power rules all. Naruto would have to find a way to balance Frieza's power without losing his own values. His training would take a whole new turn as he tries to master Frieza's power. And there could be a lot of internal conflict as Naruto battles with Frieza's consciousness inside him, trying not to let Frieza take over his body.
Well, he might gain some spooky powers. Maybe he could use the Shinigami's abilities to sense death or even communicate with the dead. It could also put him in a really dangerous situation, as the Shinigami's power might be too much for him to control at first.
In fanfiction, if Juubi Naruto was sealed in him, he might gain an incredible amount of power. This could potentially make him nearly invincible. He could have enhanced physical abilities, such as super strength and speed. His chakra reserves would likely be off the charts, allowing him to perform powerful jutsu without much strain. However, it could also come with risks. The power might be too much to control, leading to a struggle between the host and the Juubi's influence.
Well, Naruto would likely face a huge internal struggle. Majin Buu's chaotic nature might constantly try to take over Naruto's body. Naruto's own strong willpower, like what he showed against the Nine - Tails, would be put to the ultimate test. He'd probably have to deal with sudden surges of power that are difficult to control.
Well, it could make for a really interesting story. Naruto having greed sealed in him might cause him to make some uncharacteristic decisions. Maybe he'd start being more competitive in a negative way, like trying to outdo Sasuke not just for the sake of friendly rivalry but out of pure greed for power. His interactions with his mentors like Kakashi would also change. Kakashi would probably notice this new side of Naruto and try to help him overcome it.
Well, it could be really chaotic. Naruto already has a powerful force within him with the Nine - Tails. If Sans was sealed in him too, Naruto might gain Sans' unique abilities like his teleportation and bone attacks. His fighting style would become extremely unpredictable, mixing ninja techniques with Sans' skeletal powers.
Well, Naruto might gain some new powers or knowledge from having Tobi sealed. Maybe he could access Tobi's memories and use that information to prevent future threats.
Well, one possibility could be that Naruto gains new powers related to the Nibi. He might be able to use some of its unique chakra abilities, like enhanced speed or stealth. Maybe he could also communicate with other Nibi - related things in the Naruto world.
Well, Naruto's powers would likely be drastically altered. He might gain some of Jenova's abilities, like regeneration or the power to infect others with her cells. His personality could also change as he struggles to control this new, alien power within him. The other characters in the Naruto universe would be very suspicious and maybe even afraid of him.
In some fanfictions, if Naruto was sealed in the Shinju, it could lead to a major shift in the power balance. His friends might go on a desperate quest to free him. The ninja world could be plunged into chaos as his absence leaves a huge void in terms of power and leadership.