It has to be Naruto himself. His positive attitude and never - give - up spirit would be a fresh addition to the GTA world. He would be constantly trying to make the place better, trying to stop the crime not just with force but also by winning the hearts of the people. His ability to make friends easily would also lead to some really interesting relationships with the diverse characters in the GTA world, from the criminals to the law - enforcers.
I think Rock Lee would be really interesting. His extreme dedication to training and his unique fighting style would be a great contrast to the often chaotic and self - serving characters in the GTA world. He could run around the GTA streets, challenging the thugs to combat and trying to uphold his ninja code in a very different and morally ambiguous environment.
Naruto himself would be very interesting. His energetic and determined personality would make for great adventures in the GTA world. He would probably approach the chaos and crime of GTA with his usual enthusiasm, trying to bring justice in his own ninja - way. His ability to make friends easily could also lead to some interesting alliances with GTA characters.
I think Kakashi would be a great choice. He's already a very versatile character. If he had Frozone's ice powers, he could combine it with his Lightning Blade technique. He could freeze enemies in place and then finish them off with his lightning - enhanced sword. His intelligence would also make him very creative in using these new powers.
Definitely Naruto and Hulk. Just imagine Naruto trying to calm down the Hulk when he's angry. It would be hilarious. And on a more serious note, Naruto's positive energy might have an effect on the Hulk. Also, Sakura and Captain America. Sakura is a strong - willed and powerful female character, and Captain America is a symbol of leadership and justice. They could bond over their shared values and exchange fighting strategies.
Scorpion from Mortal Kombat could be a very interesting character in this crossover. His hellish powers and his quest for revenge could put him at odds with some of the Naruto characters. His battles with Naruto or Sasuke would be intense, especially with his ability to teleport and use his kunai chain.
Naruto and Ruby would be an interesting pairing. Naruto's positive attitude and never - give - up spirit could mesh well with Ruby's determination. They could both inspire each other in combat and in their personal growth. Another good pairing could be Sasuke and Blake. Sasuke's brooding nature and his search for power could be contrasted with Blake's own past and her fight for equality. They could have some deep conversations about their motives and past traumas.
Hawkeye and Sasuke would make a cool pairing. They are both very skilled in ranged combat. Hawkeye could learn some of Sasuke's Sharingan - enhanced archery skills, and Sasuke could be interested in Hawkeye's high - tech arrows. Also, Iron Man and Kakashi would be an interesting match. Iron Man's love for technology and Kakashi's use of Sharingan - based tech like his Ninja Hound summons could lead to some great interactions. They could even collaborate on creating new gadgets for both universes.
I think Sasuke and Tygra would make a great pairing. Sasuke has his Sharingan and his complex personality, while Tygra is a strategic thinker with his own set of skills. They could have some intense battles together against common enemies, and also have deep conversations about power and purpose. Also, Kakashi and Panthro would be cool. Kakashi's vast knowledge of ninjutsu and Panthro's mechanical expertise could lead to some interesting exchanges and combined efforts in combat.
Naruto himself would be very interesting. His naive yet pure-hearted nature would be in direct contrast to the dark power of the Death Note. He would struggle with the moral implications of using it, and it would be fascinating to see how he would try to find a way to use it for good, if at all.
Kakashi could be an interesting addition too. His calm and collected demeanor, along with his vast knowledge and skills, would be very useful in the new and strange world of Kuroinu. He could serve as a mentor figure not only to the Naruto characters but also potentially to some of the Kuroinu characters who might be in need of guidance.
I think Naruto and Maka would be an interesting pairing. Naruto's energetic and determined personality combined with Maka's focus on collecting souls and her academic side would create an interesting dynamic. They could learn a lot from each other, like Naruto teaching Maka about perseverance in the face of impossible odds, and Maka showing Naruto the importance of knowledge in combat.