Sakura's reactions can vary. Sometimes she tries to get revenge on Naruto for his pranks. If he plays a prank that makes her look silly in front of Sasuke, like the fake love letter prank, she'll be really mad and try to think of a way to make Naruto pay. Sasuke might pretend not to care, but if the prank affects his image too much, like the hair product switch, he'll give Naruto a cold stare. Kakashi is more laid - back and just watches the whole thing unfold like it's entertainment.
In many fanfictions, Sakura's initial reaction to Naruto's pranks is anger. But as time goes on, she starts to expect them and sometimes even finds them a bit endearing. Sasuke, who is always trying to maintain his cool exterior, will often just roll his eyes at Naruto's antics. Kakashi, being the more experienced and mellow one, might use Naruto's pranks as a teaching moment, showing the team how to handle unexpected situations with grace.
Well, in some fanfictions, Naruto has been known to put salt instead of sugar in Sakura's tea. She takes a big sip and spits it out right away, which is quite funny. Also, he might play a prank where he makes it seem like Sasuke has a crush on Sakura by leaving fake love letters from Sasuke around. It causes all kinds of chaos and blushing between the two of them.
Well, Sasuke might initially be a bit shocked but then he'd try to hide his concern. Sakura would be very empathetic and might immediately want to do something to help Naruto. Kakashi, being the experienced one, would take a more calm and strategic approach to deal with Naruto's situation and protect him from further abuse.
Sasuke might initially be indifferent on the surface, but deep down he would feel a sense of loss. He has always had a rivalry with Naruto, and Naruto's departure would mean an end to that dynamic. Sakura would be devastated. She has grown to care about Naruto as a friend and teammate, and his leaving would leave a big hole in the team.
Naruto could enlist the help of his friends like Shikamaru. Shikamaru could come up with a really elaborate plan. For example, they could set up a fake mission where Ibiki thinks he's in charge, but it's all just a setup for a series of pranks. They could have actors pretending to be enemy ninjas who act really silly instead of being threatening. And Naruto could keep popping up in unexpected places during this 'mission' to further annoy Ibiki.
One of the funniest pranks could be that the Kyuubi makes Naruto's clones start singing cheesy pop songs instead of following his commands. Naruto often uses his clones in battles and for various tasks. So when he sends them to attack an enemy, they all start singing and dancing instead. This would not only be a shock to Naruto but also to his opponents. Another great prank would be the Kyuubi making Naruto's body move in the opposite direction of what he wants. So when he tries to jump forward, he jumps backward instead, leading to all sorts of comical situations.
Sasuke would likely be devastated. Despite their past differences, Naruto was his rival and in a way, his closest friend. He might go into a deep state of regret and isolation. Sakura would be heart - broken. She loved Naruto, and his death would be a huge blow to her. She might become more withdrawn and focus all her energy on her medical ninjutsu. Kakashi would be filled with a sense of failure. He was Naruto's teacher, and he would feel responsible for not being able to protect him.
Sakura would be heartbroken. She'd likely spend hours upon hours by Naruto's side, trying to jog his memory with stories of their adventures together. She might even get a bit overbearing in her attempts. Sasuke, who has his own complex relationship with Naruto, would be conflicted. He'd see Naruto's forgetfulness as a sign of weakness at first but then realize the importance of their bond. Kakashi, being the experienced leader, would start by observing Naruto carefully to see exactly how much he has forgotten and then start a systematic process of helping him remember.
One of the pranks Naruto might do is to mess with the Anbu's communication system. He could use his knowledge of chakra and some basic electronics (if we assume some modern - like elements in the fanfiction) to scramble their signals. This would make it difficult for them to coordinate with each other, and they'd be running around trying to figure out what's wrong while Naruto watches from a hiding place, having a great laugh.
In a Naruto pranks Hyuuga fanfiction, Naruto might use his typical mischievous tactics. For example, he could use his shadow clone jutsu to create chaos around the Hyuuga compound. Maybe he'd make clones that pretend to be important visitors and then act all silly to embarrass the Hyuuga. It would be a really funny scenario as the serious Hyuuga clan tries to deal with Naruto's antics.
Naruto and Shikamaru would have an interesting relationship. Shikamaru might find Naruto's impulsiveness annoying at first but would later learn to appreciate his determination. Naruto, on the other hand, would respect Shikamaru's intelligence and might try to learn some strategic thinking from him. With Choji, Naruto would bond over food very quickly. They could have eating contests and in the process, become really good friends. As for Ino, Naruto would probably have a bit of a rocky start. Ino might see Naruto as a bit of a nuisance, but as they go on missions together, she would see his good heart and they would become friends too.