Sasuke would be a great character to pair with Naruto in this type of fanfiction. Their rivalry could be enhanced with the addition of the Boosted Gear. Sasuke might be initially jealous of Naruto's new power but then see the potential of working together to defeat a common enemy.
It could be Orochimaru. He might be interested in the Boosted Gear's power and try to steal it from Naruto. He has always been after powerful artifacts and new sources of power, so the Boosted Gear would be a great target for him.
There might be new antagonists created specifically for this fanfiction. They could be characters who are after the boosted gear for their own evil purposes. Maybe they want to use it to take over the ninja world or something. These new antagonists would likely have their own unique powers and abilities that would make them a challenge for Naruto and his friends.
One interesting Naruto Boosted Gear fanfiction could be about Naruto obtaining the Boosted Gear and using its power to face new and stronger enemies in the Naruto universe. For example, he might use it to take on a powerful Akatsuki member in a unique way.
Another character could be Kakashi. Kakashi's wisdom combined with Byakuya's combat skills and Naruto's determination would make for a really engaging story. Kakashi could study Byakuya's techniques and try to incorporate some of that into Naruto's training, while also trying to understand Byakuya's motives in the Naruto world.
One idea could be Naruto obtaining the Boosted Gear and using its power to enhance his shadow clones. The clones could then have a unique power boost that gives them an edge in battles. Another could be Naruto using the Boosted Gear's abilities to travel between dimensions, leading to encounters with different versions of himself.
One interesting aspect could be how Naruto's existing powers interact with the boosted gear. Maybe it gives him a new level of speed and strength that he uses to defeat powerful enemies in a really unique way.
Another good pair could be Kakashi and Eminem. Kakashi is a very laid - back yet highly skilled character. His calm demeanor could contrast well with Eminem's energetic and often angry - inspired lyrics, leading to some unique exchanges and perhaps even Kakashi learning a thing or two from Eminem about expressing emotions.
Naruto himself could be a great character to pair with Magneto. Their different powers and personalities would create an interesting dynamic. Naruto's positive and determined attitude could contrast with Magneto's more serious and sometimes harsh nature. Also, they could learn from each other's combat styles and strategies.
Sakura could be a great character to pair with them. She has her medical ninjutsu skills which could come in handy during their adventures. For instance, if they get injured during a battle, she can heal them quickly. Also, her strong - willed personality adds an interesting dynamic to the group.
I think Naruto and Kakashi would also work well. Kakashi is already quite intelligent and has a lot of experience. He could be like Holmes, guiding Naruto, who is like a young and eager Watson. Naruto's enthusiasm and his unique ninja skills could add a new dimension to their detective work. For instance, Naruto could use his Rasengan to break through obstacles during their investigations.