Sasuke would be annoyed at first. He sees Naruto's new interest as a distraction from their real goals as ninjas. But as Naruto becomes more skilled by adapting Power Ranger concepts, Sasuke would feel a bit of envy. Sakura would initially be worried that Naruto is spending too much time on this new 'hobby'. But when she realizes it's actually making Naruto more confident and better at combat, she would support him. And for the other friends like Kiba and Akamaru, they would be intrigued by the cool suits and gadgets of the Power Rangers that Naruto keeps talking about and might even want to check it out for themselves.
Sakura would probably be a bit skeptical at first. She might worry that Naruto is getting distracted from his ninja duties. But once she sees how passionate he is, she would support him and might even help him with his training regime, using her medical knowledge to make sure he's in top physical condition for racing.
His friends would be very shocked at first. Sasuke, for example, might be suspicious of this new Naruto. But once he realizes that Naruto is still the same at heart, he would start to accept it. Sakura would probably be worried about Naruto's well - being and try to find a way to reverse the change if possible.
Sakura might be a bit confused at first. She's focused on her medical ninja training and Naruto's sudden interest in Lunney seems out of left field. But she would probably be supportive in the end, especially if Naruto could show her how Lunney's ideas could be relevant to their lives. Sasuke, on the other hand, would likely be dismissive. He has his own goals and Naruto's newfangled interest might seem like a distraction to him. However, if Naruto could prove that Lunney's concepts could help in their fight against common enemies, Sasuke might change his tune.
His friends' reactions would be mixed. Naruto's closest friends, like Choji and Ino, would be really worried about him. They'd be sad to see him change into something so different from the Naruto they know. But at the same time, they would also be curious about his new powers. Sasuke, if he's around, might be a bit more aloof at first. He'd see Naruto's transformation as another sign of Naruto's growth and might even be a bit jealous that Naruto has gained these new and potentially powerful abilities.
Sasuke would probably be initially shocked. But then he'd be all about finding a solution. He might even sacrifice some of his own power to try and save Naruto. Sakura would be horrified and would immediately start researching any medical jutsu that could reverse the process.
His friends would be really confused at first. Sakura might try to use her medical ninjutsu to figure out what's wrong with him. Sasuke would be more reserved but also determined to find a way to turn Naruto back. Shikamaru would probably start thinking about all the possible reasons and solutions right away.
Kakashi would be very concerned as well. He would approach Naruto in a more calm and collected way compared to Sasuke and Sakura. He would try to understand Naruto's reasons for becoming a fan. Kakashi would then use his own experiences and wisdom to show Naruto the darker side of Doflamingo that he might be overlooking, hoping to bring Naruto back to his normal self.
His friends like Shikamaru would find it strange at first. Shikamaru is a practical thinker and yokai seem like something out of a fairy tale to him. However, if Naruto showed him some practical applications of yokai knowledge, like using yokai - inspired strategies in battles, Shikamaru might start to respect Naruto's new interest. Choji would probably be more open - minded. He'd be curious to hear Naruto's stories about yokai and might even ask if there are any yokai - related food or things to eat in the yokai world.
Sakura would be extremely proud. She has seen Naruto grow from a clumsy kid to a potential Hokage. She'd probably be right by his side, offering her medical skills to support him and also giving him advice when it comes to dealing with the more diplomatic aspects of being Hokage. Shikamaru, on the other hand, would be a bit more reserved in his reaction. He'd recognize the huge responsibility Naruto has taken on and would be ready to offer his strategic mind to help Naruto make important decisions.
In this fanfiction, perhaps Orochimaru, in one of his experiments, accidentally opens a portal to the world of the Power Rangers. Naruto, being in the wrong place at the wrong time, gets sucked in. There, he befriends the Power Rangers and starts training with them. He discovers that chakra and the Power Rangers' energy sources have some similarities. When he finally returns to the ninja world, he brings back some of the Power Rangers' fighting techniques and shares them with his comrades, which changes the way they fight battles.