His father might be extremely proud. After all, Goku has achieved so much, like protecting the Earth multiple times. He would look at Goku with admiration for his strength and kindness.
A being from a parallel Dragon Ball universe where the power levels are exponentially higher. This enemy would have a completely different set of techniques and abilities. For example, they could control the very concept of energy, not just ki, which would force Goku to adapt his fighting style in ways he's never had to before.
Superman would likely be impressed. He's used to being one of the strongest, but Goku's power levels would make him take notice. Batman would be his usual calculating self, studying Goku's moves for any potential threats or useful techniques. Flash would be excited to see someone who could keep up with his speed in a different way. Aquaman might be a bit more reserved, but still interested in this new kind of fighter from another universe.
Gohan would be really surprised, but being the kind - hearted person he is, he would try to understand and help out. He could offer to train with them in a more gentle way to keep them fit during the pregnancy. Piccolo would be more of a silent observer, but still be there in case of any threats.
The reaction among fans would be quite mixed. Some die - hard fans of the original series would be appalled as they have a clear image of ChiChi and Goku's relationship. They would see this type of fanfiction as a perversion of the original concept. On the other hand, there are those who are more open - minded and might see it as an interesting, if not controversial, exploration of the characters. But overall, the negative reactions would probably outweigh the positive ones.
Goku would be a mix of angry and worried. His Saiyan blood would make him want to rush into battle with Raditz right away. But he also knows how dangerous Raditz is, so he might first try to gather some allies, like Piccolo. He'd be constantly thinking about Gohan and how to rescue him as quickly as possible.
Goku would likely be extremely excited. He has always had a longing to know more about his Saiyan heritage and his father. Meeting Bardock would be like a dream come true for him. He'd probably ask a million questions about his past and Saiyan culture. Chi - Chi, on the other hand, would be a bit more reserved at first. She'd be polite but also a bit cautious, as she doesn't know what this Saiyan from Goku's past might be like. But as she sees Goku's joy, she'd warm up to Bardock.