Well, Renji would likely be extremely confused at first. He'd probably stare at Ichigo for a long time trying to figure out what's going on. Byakuya would be his usual stoic self but would secretly be curious about this transformation. Ishida might initially act cold towards Ichigo as a girl, thinking it's a distraction from their real battles. But as time passes, he would see that Ichigo is still the same person inside. And as for the Captains, they would be very cautious at first, seeing it as a potential threat or a sign of some new spiritual phenomenon.
Rukia would probably be one of the first to be both shocked and amused. She might tease Ichigo a bit at first but then quickly get serious about helping him. Chad would be very accepting and offer his protection as usual. Uryu might be a bit more skeptical at first, thinking it's some kind of new Hollow trick. Orihime would be very empathetic and try to make Ichigo feel comfortable in his new form, maybe even offer to make some new clothes for him to fit his new body.
One possible plot could be that Ichigo is hit by a strange Hollow attack that not only changes his physical form to a girl but also gives him new powers. He then has to adapt to this new body while still facing the usual threats in the Bleach universe. His friends might initially be shocked but quickly accept him and help him figure out how to reverse the transformation while still using his new - girl - form - related powers to fight enemies.
Rukia would probably be both amazed and a bit worried. Amazed at the new power Ichigo has, but worried about how it might change him. Chad would see it as a natural progression of Ichigo's power and be supportive. Orihime might be a bit scared at first, but then she would see the good in Ichigo's new form and try to encourage him.
Some characters might be shocked at first. For example, her close male friends might feel a bit betrayed or confused, especially if they had a certain type of relationship with her when they thought she was a boy. But then they could come to accept and support her.
The other gumballs in the gumball machine might be very confused. They've never seen such a thing happen before. Some might be scared and think it's some sort of curse. The humans who find the girl - gumball could be initially shocked. But some kind - hearted ones might take her in and try to help her adjust. If there are any pets in the story, they might sniff her curiously, not really understanding what she is but sensing that she's different.
Nagisa's best friend might be really surprised at first. But then, being a true friend, would support Nagisa through this strange change. They would probably help Nagisa with things like choosing girl - appropriate clothes or dealing with any mean comments from other students.
Riku would probably be really confused at first. He might act a bit awkward around Sora, not sure how to treat this new female version of his friend. Kairi, on the other hand, could be more empathetic. She would likely help Sora adjust to being a girl, like teaching her about makeup or different hairstyles if that's relevant in the story's world.
The Soul Reapers in the Soul Society would see Ichigo as a major threat. They would likely mobilize their forces to either capture or eliminate him. Captains like Byakuya would be disappointed as he had come to respect Ichigo to some extent, and now would see him as a traitor.
Rukia would probably be very suspicious right away. She knows Ichigo well and would notice the strange changes in his behavior. She might try to confront him and figure out what's wrong.
Chad would be a very protective and gentle presence. He would be like an uncle to the baby, always ready to pick the baby up and play with it. His calm and strong nature would make the baby feel safe.
Orihime would probably be over - the - moon excited. She's always been a kind - hearted and emotional person. She would immediately start knitting baby clothes or making cute little charms for the baby. Chad would be very supportive as well. He would offer his strength to protect Rukia during her pregnancy. Uryu might be a bit more reserved at first, but deep down he would be happy for them. He might use his Quincy skills to create some sort of protective item for the baby.