Goku in the manga doesn't hit a power level of 8000. The power escalation in the story doesn't go that high for him. There are various factors and story arcs that determine his power growth, but 8000 isn't one of them.
Obviously, Goku is one of the main characters. Since it's about him being born with a high power level. And his parents might also be important characters as they would be related to his birth and the discovery of his high power level. Maybe there are also some Saiyan elders or trainers who play a role in his life as they would be interested in his power.
Goku's power is measured in different forms and levels in his universe. When it comes to Legendary Pokemon, some of them have the ability to control elements like time and space. In a fanfic, Goku in his Super Saiyan Blue form might be able to match the power of a Legendary Pokemon like Palkia, which has power over space. But it also depends on the situation. If Goku is in an environment where his Ki attacks are less effective, like in a dimension where psychic powers are dominant, he might have a harder time against a Legendary Pokemon like Lugia. Overall, it's a complex comparison as their powers are quite different in nature.
In the context of this fanfiction, his high - born power level would have a huge impact on his early days. He may grow up faster in terms of physical strength and combat skills. Since he's born with such power, he might not face the same challenges as other Saiyans in developing basic abilities. However, this could also lead to overconfidence. And perhaps he has to deal with the burden of high expectations from his community at a very young age. He might be constantly pushed to test his limits, which could be both a good and a bad thing for his development.
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.
Some fanfictions might have a plot where Goku and Naruto are in a training - like fight. They exchange techniques and learn from each other. For example, Goku could teach Naruto about ki control, and Naruto could show Goku how to use chakra in a more strategic way. Their fight could be less about winning and more about mutual growth and respect for each other's abilities.
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.
Well, Goku's power level progression could be different in that he might be more in control of it. Since the head injury had some impact on his psyche, without it, he could have a more calculated approach to increasing his power. He might not rely as much on the Kaioken technique, which was developed in part due to his need to overcome limitations caused by his injury - affected development. Instead, he could focus more on pure Saiyan power - up methods like the Great Ape transformation and evolving it further.
In a Naruto - Goku fusion fanfic, the power - ups could be really exciting. Since Goku has his Zenkai boosts, and Naruto can gain more chakra and power as he progresses in his ninja journey, the fusion might have a new type of growth system. For instance, every time the fusion is in a tough battle, it could gain a permanent boost in strength, speed, and energy. Also, the fusion could potentially access a new form that combines the Super Saiyan transformation and the Nine - Tails' chakra mode for an insanely powerful state.
In a fanfiction battle, perhaps the fight begins with Naruto trying to talk to Goku first, to understand his intentions. Goku, not really understanding Naruto's world, just wants to test his strength. So he attacks without warning. Naruto quickly enters his Nine - Tails Chakra Mode to defend himself. The fight then escalates as Goku powers up further. The two exchange blows, with Goku's punches creating shockwaves and Naruto's attacks leaving marks on the ground. As the fight goes on, they both start to respect each other's power and skills, and it becomes more of a battle of wits as well as strength.