In my opinion, it's highly unlikely. Goku has mastered multiple forms and techniques that give him a wide range of powers. Saitama's one-punch style might not be effective against Goku's diverse skills and battle experience.
I don't think there's a clear winner. Both Manga Goku and Manga Saitama have unique and powerful abilities. It could come down to strategy, luck, or even the author's imagination!
One common theme is the clash of different power systems. Star has her magic from the 'Star vs the Forces of Evil' universe, and Goku Black has his Saiyan powers from Dragon Ball. Another theme could be the exploration of good and evil. Goku Black is a villain, so stories might focus on how Star and her friends deal with his malevolence. Also, the idea of interdimensional travel can be a theme, as Goku Black is from a different universe in Dragon Ball and would have to cross into Star's world.
Tornado of Terror would likely be one of the first to try and take on Evil Saitama. She's powerful and confident, but she would soon realize the extent of his power. Mumen Rider, despite being weak, would still stand up to Evil Saitama out of a sense of justice. He would be quickly defeated but his act of courage might inspire other heroes to step up.
Well, I don't have a specific title off - hand. But a good place to start looking for 'Star vs the Forces of Evil Goku Black' fanfiction is Archive of Our Own. They have a wide range of fan - created works. You can filter by the relevant fandoms and look for stories that incorporate both elements in an interesting way, like maybe a story where Goku Black ends up in the dimension of 'Star vs the Forces of Evil' and causes chaos.
A 'evil saitama fanfic' likely involves re - imagining Saitama's character in a negative light. In the original, Saitama is a rather simple - minded and bored hero who just wants a good fight. But in this fanfic, he could be turned into a villain who uses his power to bully or manipulate others. It might also delve into his backstory to find reasons for this transformation, like if he had some sort of bad experience in the past that finally pushed him over the edge. Maybe he starts causing chaos in the city he once protected, and the heroes have to figure out a way to stop him without getting instantly defeated by his one - punch power.
Well, in these fanfics, Bulma might be an important character. She could use her intelligence to create some sort of device or plan to stop Evil Goku. Also, Piccolo would be there. His strategic mind and powerful attacks would be crucial in the fight. And of course, there might be new characters created specifically for the fanfic, like a mysterious sage who knows the secrets to defeating Evil Goku.