One possible plot could be that Goku somehow gets transported to the Bleach universe. He might initially be confused by the concept of Hollows and Soul Reapers. But then, with his power, he could start fighting Hollows, thinking they are some sort of new villains. His ki-based attacks would be a new and powerful force in the Bleach world, and he could end up teaming up with Ichigo to fight a common, extremely powerful enemy, like a super - powerful Hollow that even the Soul Reapers are having trouble with.
Definitely Orihime. She is the type who would be easily attracted to Goku's pure - heartedness and his determination to protect. Her own insecurities might be soothed by Goku's confidence. Rukia, with her sense of duty, could find herself drawn to Goku's selfless acts of heroism. And Neliel could also be part of the harem. Her child - like form and yet powerful true form would create an interesting relationship with Goku, as he might be protective of her in her child form and respect her power in her true form.
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.
One idea could be a story where Goku is transported to the Bleach universe and somehow ends up attracting a harem of female characters from Bleach. For example, Orihime could be intrigued by Goku's incredible strength and kind heart, and gradually develop feelings for him. Another could be that Goku saves Rukia from a powerful enemy in the Bleach world, and as a result, she and other female Soul Reapers start to follow Goku around, leading to a harem - like situation.
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 and Aizen would be an interesting pair. Aizen is a master manipulator, and when he first encounters Goku, he would try to use Goku for his own ends. But Goku, being pure - hearted, would see through Aizen's schemes. Their interactions would be a battle of wits as well as power. Goku's straightforward nature would be a contrast to Aizen's devious ways, and it would be fascinating to see how Goku would deal with Aizen's illusions and mind games.
He'd probably be shocked by the different power systems. Naruto is used to chakra and jutsus, while Bleach has spiritual energy and zanpakutos. So it would be a big change for him to read about.