His friends like Sasuke and Sakura could be his allies. Sasuke might be initially skeptical but then see the potential of Naruto's arcane power in fighting common enemies. As for enemies, Orochimaru could be interested in Naruto's power for his own experiments. He might try to capture Naruto to study and steal his arcane abilities.
In Naruto fanfiction, one common power - up is related to new jutsu creation. For example, some fanfictions might have Naruto develop a jutsu that combines the power of all five chakra natures in a completely unique way. This could give him an edge over his enemies like never before. Another aspect could be the enhancement of his Sage Mode. Maybe he finds a way to make it more stable and powerful, allowing him to stay in the mode for a much longer time without any negative side effects. There are also fanfictions where Naruto gains the ability to control time, which is a completely new and overpowered concept that makes for really interesting stories.
One plot idea could be Naruto discovers his arcane power during a mission in a hidden ancient ruin. He has to learn to control it quickly to defeat a new, powerful enemy that is immune to his normal ninja skills. Another could be that his arcane power is tied to an ancient prophecy, and he must fulfill certain tasks to fully unlock it while dealing with those who fear his newfound strength.
In certain fanfic concepts, Naruto could get the phoenix power during a near - death experience. His strong will to survive and protect his friends could attract the phoenix spirit. The phoenix, known for its rebirth and powerful abilities, might choose Naruto as its host, seeing his indomitable spirit as a worthy vessel for its power.
Well, it could be that Naruto's strong will and his connection to all the other tailed beasts play a role. Since he has befriended the other tailed beasts, their combined energy or some sort of spiritual link might attract the power of the Juubi. For example, in some fanfic concepts, the tailed beasts' collective consciousness decides to merge their powers with Naruto, which includes the Juubi's power as the ultimate form of chakra.
In a fanfiction, Naruto having the power of the sun could potentially have a huge impact on the chakra system. Since the sun is such a powerful energy source, it might disrupt or enhance the existing chakra flow. He could develop new jutsu that are based on solar energy rather than just the normal chakra types. This could lead to a whole new set of skills and abilities that are unique to him, and it would force his opponents to completely re - evaluate their strategies when facing him.
He could have a 'Solar Sage Mode'. In this form, his body would be surrounded by a bright, sun - like aura. His physical abilities such as strength, speed, and agility would be enhanced to an extreme level. His attacks would also carry the power of the sun, like solar - powered punches or kicks that could cause massive damage.
In such a fanfiction, Naruto might start to reshape the ninja world entirely. He could create new jutsus that are unimaginable with normal power limits. He could also travel to different dimensions effortlessly to learn more about the secrets of chakra and ninjutsu, and then bring back that knowledge to improve the lives of everyone in his own world.
One drawback could be that it might disrupt the balance of powers in the Naruto world. Naruto was already a powerful ninja, and adding Sans' powers could make him overpowered compared to others, which might make the story less interesting as there would be less of a challenge for him.
If Naruto had Wolverine's power in fanfiction, it would change his fighting style completely. He'd no longer have to rely solely on his chakra. His adamantium - like claws could cut through the toughest defenses in the ninja world. Also, his endurance would be off the charts, allowing him to fight for days without getting tired, just like Wolverine.