One of the most dangerous challenges is the lack of proper guidance. Without a teacher, he could easily misuse chakra and harm himself. For instance, when he first tries to perform more complex jutsus, he might not know the limits of his body and chakra reserve.
Another dangerous challenge is the mental pressure. He is constantly aware of being an outcast in the village. This feeling of isolation can make him doubt himself during training. If he gives in to this self - doubt, it could stop his progress and even make him give up training altogether, which would be very dangerous considering his big dreams.
The environment is also a big challenge. The forest where he trains is full of wild animals and potential traps. He could be attacked by a large beast while he is concentrating on his training, and with his relatively low level of skills at a young age, it could be life - threatening.
Well, in some fanfictions, Naruto leaving Konoha for training means he has to face new enemies outside the village. These enemies might be more powerful or have different fighting styles that he's not used to. Also, he has to manage his resources on his own. Without the support of Konoha, getting food, water, and training equipment becomes a problem.
One big challenge could be gaining the respect of the older and more traditional ninja in the village. They might be skeptical of his youth and inexperience. Another could be dealing with political intrigue within the village and from other villages. Since he's young, they might think they can manipulate him.
It also makes Naruto empathetic. Because he has been through so much struggle alone, he can understand the pain and loneliness of others. When he meets people like Gaara, who also had a difficult childhood, he can immediately relate to them. This empathy helps him in forging alliances and bringing people together, which is important for his goal of becoming Hokage and uniting the village.
One major challenge could be the powerful and malevolent creatures that inhabit Tartarus. Monsters like the Titans or other ancient evils would try to stop him. They are much stronger than the usual foes he faces on the surface. Another challenge is the very nature of Tartarus itself. The place is designed to be inescapable, with its dark magic and chaotic environment constantly working against Percy.
One challenge could be facing powerful new enemies. In fanfiction, authors often create unique and formidable foes for Naruto. These enemies might have strange powers or abilities that Naruto has never encountered before, forcing him to quickly adapt his fighting style. Another challenge could be the moral dilemmas. He might have to make tough decisions in the chaos of war, like whether to sacrifice a few to save many.
Naruto would face the psychological challenge of fighting alone. He is used to having his friends by his side. Without their support, he might have moments of self - doubt. The army might also use psychological warfare against him. They could taunt him or try to make him angry to disrupt his focus. In terms of actual combat, the coordination within the army could be a big obstacle. If they are well - organized and work together effectively, they could set up complex traps and ambushes for Naruto. And if the army has access to some sort of large - scale destruction jutsu, Naruto would have to find a way to either avoid it or counter it.
One challenge could be getting the necessary resources. Uzushiogakure was destroyed long ago, so finding materials to build the village again would be tough. He might have to negotiate with other villages for supplies.
He might face the challenge of overtraining or undertraining. Since he doesn't have a coach or a training partner to tell him when he's doing too much or too little, he could end up either exhausting himself or not making enough progress. In fanfiction, he could also struggle with loneliness. Training by himself means no one to share his frustrations or small victories with. This loneliness could potentially affect his mental state and in turn, his performance. Additionally, without feedback from others, he may develop bad habits in his training that could be hard to correct later on.
Well, Naruto uses his ninja skills. He could find a sheltered spot to train in, like a cave, which offers some protection from the cold wind. Also, he may have learned some survival techniques. He could make warm drinks from local plants or animals if it's in a more wilderness - like setting. And of course, his physical strength and endurance play a big role. The more he trains, the more his body can adapt to the cold.
One challenge could be leadership. As a Jounin, he'd have to lead teams. Naruto has always been more of a lone wolf in some ways, so coordinating and guiding others might be tough. Also, there would be more complex missions. He's used to straightforward 'beat the bad guy' type of missions, but now he has to deal with politics and long - term strategic goals.