One interesting concept could be a power - level crossover. For example, how would Naruto's chakra - based powers stack up against the Saiyan power levels in DBZ. Maybe Naruto's ability to create multiple clones could be a strategic advantage against the brute force of DBZ characters.
Well, if we consider the power - scaling in their respective universes, Goku has fought opponents on a galactic level. However, Naruto has also faced extremely powerful foes within his own world. If Naruto could somehow use his Sage Mode and Kurama's chakra in a really efficient way, he might stand a chance against Goku. But Goku's experience in combat across different planets and his instant transmission ability would also be major factors in a fight.
Goku might respond with his usual naivete and excitement. He'd probably be entertained by the new and wacky versions of himself and his friends in the fanfiction. Vegeta, on the other hand, would likely be furious at any portrayal that made him seem less than the proud Saiyan prince he is. Piccolo might be more indifferent, but still a bit curious about how the fanfic writers came up with some of their ideas.
Definitely not a true story. FNAF is a work of fiction that takes place in a fictional world with its own set of rules and scenarios. It's all about creating a thrilling and immersive gaming and storytelling experience, not reflecting reality.