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!
It's really hard to say. Goku has the ability to keep getting stronger through intense battles and transformations. However, Saitama has the power to defeat any opponent with just one punch. If we consider Goku's Super Saiyan Blue form, he has an incredibly high power level. But Saitama's strength has no known limits yet. It could go either way depending on the circumstances of the fight, like if Goku has time to power up or if Saitama can land his punch first.
Well, if we consider Goku's experience in fighting different types of powerful enemies across the universe, he might have an edge in terms of strategy. However, Saitama's raw power is seemingly limitless. In a fanfiction fight, it could depend on the situation. If the fight takes place in a place where Goku can draw energy from the surroundings easily, like a planet with a lot of ki, he might be able to keep up with Saitama. But if it's a straightforward brawl, Saitama's one - punch could potentially end it all.
Saitama-sensei didn't have a mosquito fight in One Punch Superman because Saitama-sensei was a fictional character whose story and plot were adapted from manga and anime. In the manga and anime, Saitama-sensei did not fight mosquitoes. He won the game by relying on his strength and skills rather than relying on the help of mosquitoes. If you want to know more about Saitama-sensei, you can search for related manga and animation works.
I think Saitama is stronger. His power is seemingly limitless and he has never struggled in a fight. Goku, although powerful, has had many intense battles where he was pushed to his limits.