Sakura is very likely to help. She's a skilled medical ninja and has always been there for Naruto. She would use her medical jutsu to try and heal his wounds. Kakashi too. He has a lot of experience and would be able to protect Naruto while he's injured. Also, Sasuke might come to Naruto's aid. Despite their past differences, they have a deep bond, and Sasuke would not let Naruto die if he could help it.
Sakura is a very likely character. As a skilled medical ninja, she has the knowledge and ability to treat Naruto's injuries. In many fanfictions, she is often the first to rush to his side and use her medical jutsu to stabilize him.
Often, a fanfiction might have Naruto severely wounded during a training accident that goes horribly wrong. He might be trying a new and extremely powerful jutsu that he's not fully mastered yet. This could result in him being in a critical condition. His friends and mentors then have to figure out how to heal him and deal with the consequences of his over - ambition in training.
Sasuke is very likely to be involved. Given their complex relationship, Sasuke could be the one who finds Naruto severely injured and has to make a choice between helping him or leaving him. Another character could be Sakura. As a medic - ninja, she would be the one to try and heal Naruto's severe injuries. Kakashi too might be involved, either as a mentor figure who tries to figure out what happened to Naruto or as someone who has to step in to protect Naruto from further harm while he is injured.
Jiraiya, if he were still alive in the fanfiction, would be a crucial character to help Naruto. He was Naruto's mentor and had a vast amount of knowledge. He could use his sage techniques to both protect Naruto and find a way to heal his wounds. Tsunade, as the Hokage, would also mobilize all available resources in the village to ensure Naruto's safety and recovery. Shikamaru, being one of the more intelligent characters, would come up with plans to deal with the situation while Naruto is wounded.
His butler, Kuroba Toichi, if still alive in the fanfiction world, would surely come to his aid. He has a lot of experience and resources, and his loyalty to Kaito Kid would make him a natural choice to help him when he's hurt, whether it's by providing medical assistance or getting him out of a dangerous situation.
Even some of the antagonists could potentially help Jaune if there is a complex relationship developed in the fanfiction. For example, if an enemy realizes that Jaune's death or continued injury would disrupt some sort of balance, they might step in to heal him, albeit reluctantly.
Hermione would definitely be one of the first to help. She's extremely intelligent and well - read in magic, so she'd quickly start looking for spells or potions to heal Harry. She'd also stay by his side to comfort him and keep his spirits up.
Nobara Kugisaki and Megumi Fushiguro could also be among those who help. Nobara is a strong - willed and capable sorceress. She would be concerned about Nanami's well - being and use her skills to assist him. Megumi, being a calm and intelligent sorcerer, would likely come up with a plan to rescue or heal Nanami. They all share a sense of comradeship within the Jujutsu Kaisen world.
Iruka sensei could also be very helpful. He has always been like a father figure to Naruto. He would support Naruto through this strange transformation, offering advice on how to handle the reactions of others in the village and how to adapt to this new situation without losing sight of his ninja goals.
Iruka - sensei would be very likely to help. He was Naruto's first teacher and has always cared about him. He could use his teaching skills to reteach Naruto things he's forgotten. Hinata would also be there for Naruto. Her love for Naruto is strong, and she would do anything to help him. She might use her Byakugan to look for any physical problems in Naruto's body that could be related to his memory loss. And of course, Jiraiya. If he were still alive in the fanfiction, he'd be a great help. He trained Naruto and knows him well, so he could use his sage knowledge to assist in getting Naruto's memory back.