Naruto would probably be very curious about the elf girl. He'd be asking her all sorts of questions about her ears, her magic, and her elf village. The elf girl might be a bit shy at first, but Naruto's friendly nature would soon put her at ease. They could start by sharing food, Naruto introducing her to ramen, and the elf girl sharing some elven delicacies.
In a fanfiction, their interaction could start with a misunderstanding. The elf girl might mistake Naruto's headband for some kind of weapon or symbol of aggression. Naruto would then have to explain what it means to be a ninja and that he's there to protect. As they get to know each other, they could start training together. Naruto could show the elf girl some of his ninja moves, and she could teach him how to move more gracefully like an elf. Their relationship could grow from mutual respect to a deep friendship over time.
Naruto would probably be very curious about the female elf. He'd likely ask a lot of questions about her life, her powers, and her culture. His friendly and outgoing nature would make him approach her without hesitation. For example, he might say 'Hey, you're an elf? That's so cool! What can you do?' And he'd be excited to share his own ninja skills with her too.
The elf could teach Naruto about elven culture. For example, they might share their unique form of art or music. Naruto, in turn, could show the elf the ninja way of life, like how to use shuriken.
The Third Hokage might also come across Naruto in his girl disguise. He could be either amused or concerned depending on the situation. And some of the female villagers might interact with Naruto. They could either be kind and helpful, thinking he's a new girl in the village, or be a bit catty if they sense something off about this new 'girl'.
Yes, in some fanfictions, Naruto might be given unique elf abilities like enhanced archery skills, the ability to communicate with nature in an elf - like way, or even having a natural affinity for magic which is often associated with elves.
Sasuke would be really interesting. His relationship with Naruto was always complex, and if Naruto is a girl, it could add a new level of tension or even a different kind of friendship/rivalry. Sakura too. She might have a whole new perspective on Naruto as a girl, and they could form a stronger bond as female comrades. And Kakashi, his reaction to Naruto's transformation could be quite humorous and also a source of guidance for Naruto in this new situation.
Sasuke would definitely be one of the main characters to interact with Naruto. Their relationship has always been complex, and with Naruto as a girl, it could become even more so. Sakura would also interact a lot. She might be both jealous and intrigued by Naruto's new form. Kakashi too, as Naruto's mentor, would have to adjust to this change and guide 'her' in a different way perhaps.
Sasuke might be a bit standoffish towards the Powerpuff Girls at first. He's used to a more serious and dangerous world in Naruto. But as he sees their power and determination, he could start to respect them. For example, he might be impressed by how Bubbles can communicate with animals, which could be useful in a mission.
One possible plot could be that the elf girl is from a hidden elf village and she gets lost in the Ninja world. Naruto stumbles upon her while on a mission. He helps her find her way back home, and during their journey, they learn about each other's cultures. The elf girl could teach Naruto some of her magic, and Naruto could show her the power of ninja techniques.
She could interact with Naruto by being amazed at his never - give - up attitude. Naruto would be excited to learn about her magic. With Sasuke, she might have a more tense relationship at first, as he's more reserved. She could offer to teach Sakura some basic magic spells, which Sakura would be eager to learn. And with Kakashi, she could exchange knowledge about different combat techniques.
A fanfiction could be written where Stealth Elf is sent to the Naruto universe to help Naruto in his fight against the Akatsuki. Her stealth and unique powers could give Naruto and his friends an edge in the battles.