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.
In a fanfiction scenario where Sans is sealed in Naruto, the story could take many interesting turns. Naruto's friends might be initially confused or even a bit scared of the new powers and the change in Naruto. From a power - up perspective, Naruto could use Sans' power to traverse different dimensions more easily, which could be useful in exploring new areas or finding hidden secrets in the Naruto universe. And in battles, he could use Sans' special attacks in unexpected ways, like using bone projectiles as a distraction while he sets up a more powerful ninjutsu attack.
The ninja world would be in shock. The Hidden Villages would be very cautious around Naruto. They might see him as an even greater threat or an unknown entity. His friends, like Sakura and Sasuke, would have to adjust to this new Naruto and learn how to fight alongside him with his new powers.
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.
If Naruto had Sans powers in fanfiction, he would become extremely powerful. His combat abilities would be enhanced greatly. He could use Sans' teleportation skills to quickly move around the battlefield, catching his enemies off - guard. His attacks might also gain some of Sans' unique characteristics, like the ability to bypass defenses in unexpected ways.
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.
The power balance in the Naruto universe would be completely disrupted. Naruto would become an extremely overpowered character. Enemies that were once a threat might not stand a chance against him. Also, the villages might view him with more fear and suspicion due to the unpredictable nature of Godzilla's power.
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, 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.