He could meet some Pokemon trainers. They might come looking for the lost Pokemon egg and Naruto would have to decide whether to give it back or keep it.
It's possible that Naruto could meet some legendary Pokemon in this fanfiction. Since he has found an egg, it could be related to a very special or powerful Pokemon. Legendary Pokemon often have important roles in the Pokemon world, so they might show up to check on the egg or to guide Naruto in taking care of it. This would be a really exciting encounter for Naruto as he's used to dealing with powerful ninja abilities and now he has to deal with something completely different from the Pokemon world.
Well, Naruto might first be really confused about the strange Pokemon egg. He could try to figure out what it is and where it came from. Maybe he'd think it's some kind of new ninja tool at first.
Iruka could help. He's always been there for Naruto. He might know some old tales about mysterious eggs and give Naruto some useful tips.
He might meet an old Pokémon expert who gives him tips on hatching the egg.
Well, Naruto might take the egg to his home and try to figure out what kind of creature is inside. Maybe he'd ask Kakashi for advice on how to take care of it.
Naruto might run into a group of rogue ninjas who are using the bunker as their hideout. This would lead to a confrontation where Naruto has to use his skills to defeat them and protect the village from their potential threats.
If Naruto finds a dinosaur egg in fanfiction, he would probably be super excited. Naruto is always curious about new things. He could use his shadow clones to help him take care of the egg. And when the baby dinosaur hatches, he might train it like he trains his ninja pets, teaching it some cool ninja moves.
It could be an Eevee. Eevee is a very common yet special Pokemon. It has the potential to evolve into many different forms, so it would be an interesting addition to Fem Ash's team.
Maybe Kakashi. He's very experienced and wise. He could share some of his knowledge about strange things he has encountered before. He might help Naruto understand the significance of the egg and guide him on what to do with it, whether it's to keep it safe or to find its rightful place.
In the 'Naruto finds an egg fanfic', Naruto may take the egg to his teacher, like Iruka. They might study it together. It could be an egg of a rare creature. Naruto's sense of adventure would lead him to discover more about the egg, and perhaps it will hatch into a cool animal that becomes his new friend or ally.
He could meet the previous Hokages. Since the library is infinite, there might be records or even some kind of spiritual manifestation of them. They could guide Naruto further in his journey.