Some popular themes in Goku and Goten fanfiction could be their training adventures. They might face new and powerful enemies together and have to develop new techniques to defeat them. Another theme could be family bonding. Since they are father - son, there could be stories exploring how Goku passes on his Saiyan heritage and values to Goten.
They also develop their characters through their relationships. Goku has a unique relationship with Goten as his father. Writers might show Goku being a bit more laid - back as a dad compared to how he was with Gohan. Goten, in turn, might be shown as eager to please his father and live up to the family name. Additionally, in battle situations, their different fighting styles can further develop their characters. Goku's more experienced and instinctive style, while Goten is still learning and may be more impulsive.
Well, Vegeta would be a likely character. He might be initially suspicious of the female Goku. Maybe he thinks she's a threat or just can't believe there's another Goku - like being. He could be there to add some comical moments as he tries to understand the situation.
In some versions, the female Goku could be part of a prophecy. The two Gokus meet, and at first, there is some confusion and misunderstanding. But as they get to know each other, they discover that they are key to fulfilling the prophecy. They combine their powers and defeat an ancient evil that was threatening both of their worlds.
In a fanfiction where Future Gohan meets Goku, it could be an emotional reunion. Gohan might be filled with a sense of relief and joy, seeing his father again. He could show Goku all the things he's been through in the future, and Goku would be both proud and sad about what his son has endured.
Well, Goku could be intrigued by Spyro's fire - breathing ability. He might want to test his own powers against it, like having a friendly sparring match where Goku uses his ki blasts and Spyro his fire breath.
In a 'Vegeta meets Chibi Goku' fanfiction, it could be really fun. Chibi Goku might be curious about Vegeta's Saiyan pride and constantly ask him questions. Vegeta would probably get annoyed at first but gradually warm up to the little guy. They could also have some training sessions together, with Vegeta trying to teach Chibi Goku some of his more advanced techniques, and in the process, they become friends who respect each other's abilities.
It's really hard to say. Goku has superhuman strength and can destroy planets with his power. But Spyro has his own set of unique abilities like flying, fire - breathing, and his agility. If it's a physical strength test, Goku might seem stronger. But in a world full of magic and different terrains, Spyro could have an edge in his own territory.
In this fanfiction, perhaps Goku would have an emotional reunion. He might learn more about his Saiyan heritage directly from his mom. Maybe she would teach him some long - lost Saiyan techniques or share stories about his father that he never knew.