One possibility is that Naruto's chakra nature could change completely. Since Kaguya had unique chakra, Naruto might develop new jutsu that are a blend of his own and Kaguya's abilities. For example, his Rasengan could gain the power to not only attack but also to heal, as Kaguya had some form of life - giving power. Also, his connection to the tailed beasts could be enhanced in unexpected ways, allowing for better communication and cooperation with them.
Well, one possibility is that Naruto could use his newfound power of absorbing Kaguya along with the time travel ability to prevent some of the major tragedies in the Naruto universe. For example, he might stop the Uchiha massacre, which would change the entire course of the story. It could also lead to a different relationship between Sasuke and Naruto, as Sasuke's motivation for revenge would be gone.
Well, if Naruto absorbs Madara and Hashirama in a fanfiction, he could potentially gain an incredible amount of power. He might be able to combine the Wood - Style of Hashirama with his own Sage - Mode and other abilities. This could make him nearly unbeatable. He could also gain insights into the history and secrets that Madara and Hashirama held, which could help him further unite the ninja world. Maybe he could even use their combined powers to create a new jutsu that no one has ever seen before.
If Naruto absorbs Kaguya in a fanfic, it might lead to a very different storyline. He could use Kaguya's power to bring about a new era of peace more quickly. For example, he might be able to use her power to stop all forms of aggression instantly. Also, his appearance might change slightly, taking on some of Kaguya's physical traits. And his understanding of the chakra and the world's origin could be greatly enhanced.
Well, Naruto might first try to free Kaguya. He is a hero after all and doesn't like to see anyone chained unjustly. But he would also be very cautious because Kaguya is extremely powerful and was once a great threat. He could try to communicate with her to understand why she is chained there in the first place.
Well, in a 'naruto absorbs hinata fanfiction', Naruto could absorb Hinata's gentle and kind-hearted nature along with her skills. This might change his personality a bit, making him more empathetic. And perhaps he could use Hinata's family techniques in a new and creative way, like combining the Gentle Fist with his Rasengan.
Well, if Harry Potter absorbs the Goblet of Fire in fanfiction, he might gain some extraordinary powers. Maybe he could control fire in a way that no one else can. He could use it to protect himself and his friends from the Dark Arts. It could also make him a target for more powerful dark wizards who want to use his new power for their own evil purposes.
In this fanfiction scenario, Naruto could potentially use new and untested jutsu. He might draw on the power of his nine - tailed fox in a completely different way. Maybe he'd combine Sage Mode with some secret Uzumaki clan technique he discovers during the fight.
In this fanfiction, Naruto would likely have a huge power boost. Since Kaguya has such vast knowledge and power, she could train Naruto to better control his already massive chakra reserves. Maybe she'd show him how to use chakra in ways he never thought of before. For example, she could teach him to infuse his rasengan with some of her own unique chakra elements, creating a new and super - powerful attack. Also, Naruto's understanding of the origin of ninjas and the world itself could deepen through Kaguya's teachings.
In some fanfictions, if Naruto absorbs the Shinju, he might gain an incredible boost in power. He could potentially have access to vast amounts of chakra, far beyond what he already has. This new power might allow him to easily defeat his enemies, even those who were previously much stronger than him.
If Naruto absorbs Broly in fanfiction, it could lead to some really interesting character developments. Naruto has always been about hard work and friendship, but with Broly's power, he might face new internal struggles. For example, he could struggle with the newfound brute force that might be at odds with his ninja way. Also, his friends might be a bit wary of him at first due to this sudden and extreme power change. But in the end, Naruto would probably find a way to use it for good, just like he always does.