Naruto could also be a great caretaker in his own way. He has a big heart and lots of energy. He'd be constantly playing with baby Kakashi and making him laugh. Although he might not be as organized as Sakura, his enthusiasm would keep baby Kakashi happy and entertained.
One possible plot could be that the transformation is the result of a failed jutsu. Team 7 then has to take care of baby Kakashi. Naruto might be really excited at first, seeing it as a chance to be the responsible one for once. Sakura would be the more practical caretaker, making sure Kakashi is fed and clean. Sasuke would be a bit aloof but secretly curious about this strange situation.
In a normal Naruto - themed fanfiction world without violating the original essence too much, this would be a very strange and non - canon plot. However, if we were to imagine, perhaps some powerful jutsu or strange magic - like occurrence in the fanfiction universe could have led to this situation. But this goes against the normal relationship and character development in the original Naruto series.
The Naruto fandom would likely be very divided. Some fans might be intrigued by this unique and unexpected plot twist, seeing it as an interesting exploration of an alternate Naruto universe. However, many fans would probably be quite shocked and even appalled, as it goes against the traditional understanding of the characters and the series.
Obviously Naruto himself is the main character as he is the one who turns into a baby fox. His friends like Sasuke and Sakura would also be involved. Sasuke might be initially confused but then determined to help Naruto. Sakura would probably be more nurturing and try to take care of the baby fox Naruto. Kakashi Sensei could also play an important role, using his wisdom to figure out what happened to Naruto and how to reverse it.
Kakashi would become more nurturing. In the original, he was a teacher, but as an adoptive father, he'd have to be more affectionate. He might show his face more often to Naruto, as a sign of trust, and be more open about his emotions.
Well, in this kind of fanfiction, perhaps the Bat - family would be in a total chaos. Alfred would suddenly have to take care of a baby Batman. He'd have to change diapers, feed him, and keep him out of trouble. Robin might be really confused at first but then would probably take on a protective role like a big brother.
It could be Orochimaru. He might be interested in the baby for some dark experiment, thinking the baby has unique chakra or abilities that he can use for his own gain. He would stop at nothing to get his hands on the baby, which would put Kakashi and Sakura in a tough situation to protect it.
Their relationship could be one of mentorship from the start. Kakashi, with his skills and knowledge, could start teaching baby Naruto simple ninja concepts early on. He would also be very patient with Naruto, understanding that he's just a child and has a lot to learn.
I think Naruto would be one of the most affected. Since he and Hinata have a special connection, having her turn into a baby would completely change their dynamic. He'd have to step up and be responsible in a new way.
Lucy would be very affected. She's one of Natsu's closest friends. She'd have to take on a lot of responsibility for taking care of baby Natsu, which would disrupt her normal life of doing quests and writing her novel.