In the Dragon Ball universe, there are many strange and wonderful things. King Kai might have access to some rare or magical items. He could use one of these items to help Goku's tail grow back. For example, there could be a special fruit on his planet that has regenerative properties. When Goku consumes it or King Kai uses it in some other way, it triggers the growth of the tail.
In a Naruto fanfiction where Goku lands, it could change the entire power dynamic. Goku's friendly and competitive nature would likely lead him to spar with the strongest ninja. He could also become friends with Naruto, who shares his determination. Goku might introduce new training methods to the ninja world, based on his own intense training regime on Planet Vegeta and with King Kai. His presence could inspire the ninja to reach new levels of power, or it could cause some to fear his overwhelming strength.
If Goku landed somewhere else, it would likely lead to a whole new power-up journey for him. He might discover unique training methods or face challenges he never imagined before.
It could also be a symbol of a new power - up. In the Dragon Ball series, new physical changes often lead to increased power. So, getting his tail back might mean that Goku is about to reach a new level of strength. Maybe he'll be able to transform into a new form that is related to his Saiyan heritage and the presence of the tail. This could give him an edge in future battles against stronger opponents.
Well, he would probably be a very different person. He might be more in tune with the Saiyan warrior culture. He could be more aggressive and less empathetic compared to the Goku we know. He would grow up learning the ways of the Saiyans on Planet Vegeta, which means he'd be trained to fight and conquer from a very young age.
His power would develop more in line with Saiyan traditions. He'd probably have a stronger base power due to the intense training environment on Planet Vegeta. There would be more emphasis on raw power and combat skills from a young age.
The story would likely start with chaos as Goku's sudden appearance would be a huge shock. His actions would drive the plot. For example, if he accidentally destroyed part of a village while testing his power, the ninja would either see him as a threat or try to get his help against other enemies.
Adventure is another typical theme. They could go on adventures together, either in the Other World or on Earth. These adventures can range from fighting new villains to exploring uncharted territories. This theme allows for a lot of action and excitement in the fanfictions.
One could expect an exciting adventure. Maybe it'll involve Goku's power being used in a unique way to protect the timeline that Supreme Kai of Time oversees. It could also show a different side of their relationship, perhaps a friendship that develops as they face challenges together.
Another storyline could involve Supreme Kai of Time getting into trouble in a different timeline and Goku having to rescue her. Along the way, they discover new forms of power and new allies.