In a straight - up power comparison, Goku has the ability to reach extremely high power levels that can destroy planets. But Naruto has the power of the Nine - Tailed Fox and his Sage of Six Paths mode which also gives him immense power. If the fight takes place in Naruto's world, Naruto could use the environment to his advantage, like summoning giant toads or using the terrain. On the other hand, if it's in a more open space like in Goku's battles, Goku could use his flight and long - range attacks more effectively. So it's hard to say who would win definitively.
One possible storyline could be that Naruto is somehow transported to Goku Black's universe. There, he has to face Goku Black who sees him as an intruder. Naruto would have to quickly learn about Goku Black's powers and find a way to fight back using his ninja skills. Another storyline could be that a powerful villain creates a rift between their two universes and pits them against each other. They start off as enemies but then realize they are being manipulated and team up to fight the real villain.
There could be a storyline where Beerus, out of boredom, decides to train Goku Black instead of fighting him. But Goku Black misinterprets this as a sign of weakness and attacks Beerus. This could lead to a battle where Beerus has to hold back at first to avoid killing Goku Black, but as the fight progresses, he realizes he has to use his full power to subdue him.
In a one - on - one fight between One Punch Man (Saitama) and Goku, it's really tough to say. Saitama is known for being able to defeat any opponent with just one punch. However, Goku has a vast array of powerful forms and techniques. If Saitama landed his first punch, he'd win instantly. But Goku's speed and ability to constantly power up could potentially give him an edge. He could keep dodging Saitama's punches until he found a way to overpower him. It really depends on how the fight is set up in the fanfiction.
In a fanfiction battle between Naruto and Goku Black, Goku Black might have the advantage. He has the ability to transform into different Super Saiyan forms which greatly increase his power, speed, and durability. Naruto is strong too, with his Nine - Tailed Fox chakra and his various ninja techniques. However, Goku Black's Saiyan physiology gives him an edge in combat. His ki attacks could potentially overpower Naruto's ninjutsu. But Naruto is known for his strategic thinking, so he could find a way to outwit Goku Black if the fanfiction is written that way.
In fanfiction, it's really hard to say for sure. Different fanfictions might have different outcomes. Some might make Goku Black super powerful and give him the win, while others would keep Beerus as the dominant force due to his status as a God of Destruction.
One interesting fanfiction could be about Goku and Black Goku teaming up against an even greater threat from another universe. In this story, they might initially be at odds but gradually learn to work together, using their unique abilities to save the multiverse.
In fanfiction about Goku and Goku Black, a common concept is the alteration of their power levels. Writers may give Goku new forms or boost Goku Black's abilities in unexpected ways. There can be stories centered around Goku Black's adaptation to the main timeline's culture and society. For example, he might have to deal with the everyday life in addition to his evil plans. And there are fanfictions that focus on the psychological impact of their battles on each other, like how Goku might be affected by constantly facing an evil version of himself.
A Goku and Goku Black fusion in fanfiction could be really exciting. The fusion would inherit Goku's love for fighting and getting stronger, but also Goku Black's ambition. Their combined ki could be a new type of energy that no one has ever seen before. This new fused form might also have new transformations or abilities. For example, it could combine Goku's Super Saiyan forms with Goku Black's Rose form in unexpected ways. It could change the power balance in the Dragon Ball world and open up all sorts of new storylines, like teaming up with other characters to take on new threats or even having internal struggles between the two personalities within the fusion.
It could be insanely powerful. Goku already has incredible power levels, and Goku Black is no slouch either. When they fuse, it's like combining two nuclear reactors. Their power could be so great that they could effortlessly destroy planets just by flexing their newfound power. They might be able to reach Super Saiyan forms that are far beyond what we've seen in the official series, with power levels that are basically off the scale.