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.
Sango could also take care of Kagome. As a strong and kind - hearted woman, she would know how to nurse Kagome back to health. She might use her knowledge of herbs and remedies to make Kagome feel better. Plus, she would offer emotional support to Kagome during her illness.
Alfred would probably be the first one to take care of him. He's always there for Batman.
Thor could be one of the first to take care of Loki. Despite their differences, Thor still cares about his brother. He would use his strength to protect Loki from any threats while Loki is sick and might even search for rare remedies.
Gwen could also take care of Ben. As his cousin, she would be worried about him. She might use her magic to try and ease his symptoms or find a cure. She would probably make him some soup and keep him company while he's sick.
His best friend could be the one to take care of him. This friend would stay by his side, make sure he takes his medicine on time, and keep him company while he's sick.
In the fanfiction, it could be that Sailor Chibi Moon comes to take care of Sailor Moon. Since she looks up to Sailor Moon so much, she would do everything she can. She might even use her own little powers in a unique way to try and make Sailor Moon feel better, like creating a warm and cozy environment around her bed.
Padmé could also be involved. She is known for her compassion. She might use her resources to get the best medical help for Ahsoka. She could bring in the best doctors in the galaxy or some special remedies from Naboo.
It could be a joint effort. Zack would be there for sure, but the whole gang including Woody and London might also pitch in. London could use her resources to get the best possible care for Cody, while Woody could provide some comic relief to keep Cody's spirits up during his illness.
Carly would probably be the first one to take care of Sam. They're best friends, after all. She'd bring her soup and make sure she has enough blankets.
In this fanfiction, the Chaotix detective agency could also play a role in taking care of Sonic. Vector might not be the best at medical stuff, but he could use his detective skills to find out the source of Sonic's illness. Espio could use his stealth to keep an eye on Sonic's surroundings, and Charmy could keep Sonic's spirits up with his energetic personality.