It's hard to say for sure. Naruto in his Sage Mode or with the power of the Nine - Tails is extremely powerful. He has a vast amount of chakra and can perform powerful jutsus. However, Inuyasha with his Tessaiga, especially when it's in its upgraded forms, is also a force to be reckoned with. He has superhuman strength and speed, and the Tessaiga can cut through almost anything. But if we consider all aspects, Naruto might have an edge as he can use a wider variety of techniques and has more experience in large - scale battles.
Well, Kagome also has her own powers. Her spiritual arrows can purify demons and she has a connection to the Sacred Jewel. But compared to Naruto, her powers seem a bit more limited in terms of raw power output. Naruto has fought against some of the most powerful villains in his world. He has faced opponents who could destroy entire villages. Inuyasha and his comrades are strong in their own right in the feudal Japan setting, but Naruto's power level in his more advanced forms is just on a different scale. So, overall, Naruto would likely be the most powerful character in this crossover fanfiction.
Sesshomaru could also be a contender for the most powerful. He has incredible demonic powers, is extremely fast and strong, and his Bakusaiga is a very dangerous weapon. But when you look at Naruto's growth throughout the series, like when he mastered the power of the Six Paths. He has the ability to fly, sense danger from afar, and his attacks can cause massive destruction. So, in a crossover, Naruto's adaptability and ever - increasing power might make him the most powerful, though it would be a close fight against Sesshomaru or Inuyasha at their peaks.
Sesshomaru could also be a very powerful character in this crossover. He has his own powerful sword, Bakusaiga, and his inhuman strength and speed. He is very experienced in combat against demons. Compared to Naruto's friends like Sakura, Sesshomaru would likely be much more powerful in terms of raw strength and combat ability. But Sakura has her own medical ninjutsu and superhuman strength when she releases her inner power, which could also be useful in different situations.
In my opinion, Aizen could be one of the most powerful characters in such a crossover. His intelligence and his ability to manipulate others are already very dangerous in the Bleach universe. If he were to enter the Inuyasha world, he could easily use his wits to turn the different factions against each other. He could also potentially find a way to use the demon energy for his own gain. His Zanpakuto's powers are also very versatile and could give him an edge against the characters in Inuyasha's world.
It's a tough call, but it could be Light. If he manages to get his hands on the knowledge of the Inuyasha world and its rules, he could use the Death Note very effectively. He could target demons by learning their names, and since many demons in the Inuyasha world are vulnerable to human - like weaknesses in some ways, his strategic mind could make him a very powerful force. He could even manipulate some of the human characters in the Inuyasha world to do his bidding.
It's really hard to say. Naruto in his strongest form, like when he has the power of all the tailed beasts, is extremely powerful. He has incredible strength, speed, and the ability to use a vast array of jutsu. However, Aang in the Avatar state has access to all four elements and can be a formidable opponent. If we consider the Avatar state's spiritual connection, it could give Aang an edge in a battle of wills.
Naruto and Inuyasha themselves would be a very intriguing combination. Naruto's positive attitude and never - give - up spirit combined with Inuyasha's rough - around - the - edges but strong - willed personality would create a lot of interesting interactions. They could start off not liking each other but gradually become friends as they face challenges together.
Sasuke would also be very powerful. His Sharingan gives him enhanced perception and the ability to copy moves. In the SAO world, he could quickly analyze the fighting styles of opponents and come up with counter - strategies. His Chidori and other lightning - based jutsu could be very effective against the digital enemies in SAO.
However, we can't forget about Steve. He has been living in the Minecraft world for a long time. He has in - depth knowledge of how to build the most powerful weapons and structures. He can use his pickaxe with great skill, which could be as effective as a ninjutsu in some cases. Also, his ability to survive in the Minecraft world's harshest conditions gives him an edge over the Naruto characters who are new to this environment.
It could be Naruto in his Sage of Six Paths mode. He has incredible power, with the ability to fly, use various powerful jutsus, and his chakra is off the charts. In a fight against the characters from Toriko, his speed and strength would be very difficult to match.
In a naruto tekken crossover fanfiction, I think Orochimaru could be a very powerful character. He has the ability to use various snake - based jutsu and is a master of deception. He could potentially use his skills to outwit Tekken characters. But on the Tekken side, characters like Heihachi Mishima with his Mishima - style karate and his decades of fighting experience would also be a formidable force. It really depends on the environment and the nature of the encounter.
It's likely Naruto himself. His ability to create countless shadow clones gives him a huge advantage in battle. He can overwhelm opponents with sheer numbers. Also, his rasengan is a very powerful attack. In the Castlevania world filled with vampires and demons, he could quickly adapt his skills to take on these new foes.