Iruka - sensei would be a likely candidate. He has always been like a father figure to Naruto, so he would probably step up and take care of baby Naruto.
In the village, there are many people who could take care of baby Naruto. The Third Hokage might arrange for some reliable ninja to look after him. Maybe some of the older villagers who have seen Naruto grow up (even if they were not always kind to him before) might feel a sense of duty. And of course, Naruto's closest friends would be the first ones to jump in. They would feed him, change his diapers, and protect him from any potential threats in the village or outside.
His friends like Sakura and Sasuke could also take care of him. Sakura has a nurturing side and Sasuke, although he might act tough, would also feel some responsibility towards his former teammate. Also, Kakashi could keep an eye on baby Naruto. He has experience dealing with young ninja and would ensure Naruto's safety while he's in this vulnerable state.
Catwoman might also step in. Despite being a sometimes - villain, she has a soft spot for Batman. She could use her cat - like skills to keep baby Batman out of harm's way. And she might find the whole situation rather amusing, but still be very vigilant in protecting him.
His friends like Sakura and Sasuke might step in to take care of him. Sakura, with her nurturing side, could handle feeding and cleaning him. Sasuke, though he might seem reluctant at first, would probably also protect the baby Naruto from any threats.
Pepper would be a likely candidate. She has a close relationship with Tony already, so she'd probably step up and take care of him. She has experience dealing with Tony's antics, so she could handle baby Tony's needs too.
His teammates, Sasuke and Sakura, would surely be involved. Sasuke, although he may not show it as much, still cares about Naruto. He would keep an eye on Naruto's condition, and if there was any sign of danger, he would be ready to protect him. Sakura would be more hands - on with the medical care, checking his temperature, giving him medicine, and making sure he rests properly.
Well, in such a fanfiction, Naruto would probably be really cute as a baby. His friends might be super confused at first. Sasuke might be a bit less brooding towards baby Naruto. And Iruka-sensei would probably take on a more parental role, making sure baby Naruto is safe and cared for.
Kushina would take care of baby Naruto very tenderly. She would make sure he is well - fed before sleep, perhaps by breastfeeding him or giving him a warm bottle. She'd also check his diaper and change it if needed.
His friends would probably take care of him. Midoriya would be very eager to help, using his kind-hearted nature. He would make sure Todoroki is fed and comfortable.
I think Hulk would be the most difficult. Even as a baby, he has that temper. If he gets angry, he could cause a lot of destruction. It would be hard to calm him down, and his super strength as a baby might still be considerable, so he could break things easily.
Mercy could also be a great caretaker. She has a nurturing side as a healer. She would be able to make sure baby Junkrat is healthy and well - taken care of, using her medical skills to check on him regularly.
I think Konan would be the most likely. She has a more gentle and nurturing side compared to most of the other Akatsuki members. She could use her paper abilities to create things for the baby like a soft bed or toys.