In a more creative fanfic, an ancient ninja who was the originator of the Chidori technique could appear. This ninja could be brought back to life through some sort of magic or jutsu. He sees Naruto's pure heart and decides to pass on the Chidori knowledge to him, believing Naruto will use it for good.
Maybe Sasuke teaches him the Chidori in a moment of camaraderie. And for the Rasengan, it could be an older and wiser Naruto from the future who travels back in time to teach his younger self.
There could be many 'sakura learns chidori fanfiction' out there. Maybe you can ask in relevant anime or Naruto fan communities. They might be able to point you to some good ones. Sometimes, these fan communities have their own collections or recommendations for such fan - made stories.
One possible plot development could be that Sakura struggles at first to master the Chidori. She might face setbacks and doubts from her peers, but she perseveres.
One possible scenario could be that Naruto learns the Chidori from Sasuke in a moment of truce. Sasuke, realizing Naruto's determination to become stronger, decides to teach him this powerful jutsu. Another could be that Naruto discovers a scroll that contains the secrets of the Chidori and through his own hard work and study, he manages to master it. Or perhaps, a new character appears who has knowledge of the Chidori and trains Naruto in it as part of a greater plan to defeat a common enemy.
One possible plot could be that Naruto discovers the Chidori technique while training in a secret area. Maybe he stumbles upon some old scrolls left by Kakashi. He then has to train hard to master it, facing difficulties like controlling the lightning chakra. As he progresses, he combines it with his own unique Rasengan, creating a new and powerful jutsu.
It could be Kakashi. Since he's already Naruto's teacher and he knows both techniques. He could guide Naruto in understanding the intricacies of the Chidori, like how to form the lightning - chakra in his hand, and for the Rasengan, he could give more advanced tips on chakra control.
In a fanfiction like this, the plot might involve Naruto struggling to master both techniques. He could start by observing Sasuke use the Chidori and then try to incorporate its lightning - based power into his own jutsu. For the Rasengan, he might have new insights while training, perhaps finding a way to combine it with the Chidori for an even more powerful attack. Along the way, he would face challenges like controlling the chakra flow for both techniques and dealing with opponents who are also after these powerful jutsus.
Sasuke could be Naruto's teacher. Since Sasuke is a master of the Chidori, he might decide to teach Naruto as a way to make Naruto a more formidable ally. They have a complex relationship, and this could be a way to strengthen their bond.
Well, he might start with intense training sessions. Maybe he observes Kakashi closely for the Chidori, and for the Rasengan, he practices over and over again, gradually getting the hang of the chakra control required.