Naruto would probably be very popular. His energetic and determined personality would translate well into the modern world. He'd be the type to always stand up for what's right, whether it's against bullies in a school or corrupt businessmen in the city.
I think Kakashi would be a very popular character too. His laid - back yet highly skilled nature would be appealing. In a modern setting, he could be a mentor figure, maybe a teacher at a special school or a trainer in a private security firm, passing on his wisdom and ninja skills to the next generation.
It could be Sargeras from World of Warcraft. His immense power as a titan could be really hard for Naruto characters to deal with. He has the ability to destroy entire worlds and his magical power is off the charts.
Definitely Naruto. He's the face of the series and his growth and spirit are always appealing in modern fanfic. Hinata is also a fan favorite. In modern fanfics, her shy yet strong - willed nature can be explored in new ways, like in a modern - day romance story. Kakashi is popular too. His cool and mysterious demeanor can be used in various modern scenarios, such as being a mentor in a high - tech ninja training academy.
Sasuke could also be very popular. His cool and mysterious aura would attract a lot of attention. Girls might be drawn to his brooding nature and his exceptional skills. However, he might not be as approachable as Naruto. He'd be the loner that everyone wants to be friends with but is too intimidated to approach. Then there's Hinata. Her shy and kind nature would make her popular among the more sensitive students. She'd be the girl that many would want to protect.
I think Naruto would be a likely candidate. He's always been adaptable and open - minded. His experience with the Nine - Tails and his own growth as a ninja would help him in the Persona 3 world. He would probably be eager to make new friends and form Social Links, and his positive attitude could be a great asset when facing the Shadows.
Ino might be a popular character too. She's stylish and confident. In a college setting, she could be part of the popular clique, known for her fashion sense and her ability to charm people. She'd also be really good at networking and getting involved in campus politics.
Sakura could also be a popular character. She's smart and strong - willed. In high school, she'd be that girl who's good at academics and also has a feisty side. She can stand up for herself and her friends, and she has a growing confidence that would draw others to her.
Personally, I find Kakashi as a wolf to be the most interesting in a fanfic context. Wolves are known for their intelligence and their pack - oriented nature. Kakashi is a very intelligent character, and seeing him lead a 'wolf pack' of his comrades would be really cool. He could use his wolf - like instincts to strategize and protect his pack, just as he does with his friends in the Naruto series.
Naruto himself is often still a popular character. Even in the fanfic, his determination and growth can be a central focus, and the new character reborn into the world might interact with him in interesting ways.
Well, that's a tough one. It varies a lot. Sometimes it's the main protagonist, but sometimes it's a supporting character who steals the show. It all depends on the unique traits and storylines given to each character in the fanfic.
It could be Naruto in his Nine - Tails Chakra Mode. He has immense power and speed, which would give him an edge in the Smash Bros battles.