One challenge could be the lack of knowledge about sailing. He's used to ninja techniques, not nautical ones. Another might be dealing with traditional pirate enemies who don't understand his ninja ways. And he'd have to learn about the different cultures in the pirate world.
As a pirate captain, Naruto would face the challenge of getting other pirates to accept him. His ninja look and techniques might seem strange to them. He'd also have to deal with sea monsters and rival pirate crews. Plus, he'd need to find a way to balance his sense of justice with the more cut - throat nature of the pirate world. He can't always go in fists - first like he did in the ninja world, he needs to be more strategic at sea.
One challenge could be adapting to the team's dynamics. Team 8 has its own way of operating, and Naruto is used to his own style with his friends. For instance, they might be more methodical in their planning, while Naruto is more of a 'jump - in - and - figure - it - out' type. So, he'd have to learn to follow their lead sometimes.
One challenge could be dealing with jealous teammates. Since Percy is so talented in the water, some might envy his skills. Another is the pressure to always win. Everyone expects the team to do great with Percy as captain. Also, he might face difficulties in getting the team to work together if there are different personalities.
He might face powerful enemies. Maybe a new pirate crew with a devil - fruit user who can nullify Luffy's powers. Luffy would have to find a way to overcome this power - nullifying ability to reach Ace.
He might face challenges like finding the right place to plant the tree. Konoha has a lot of regulations about what can be planted where. Also, he needs to make sure the tree gets enough water and sunlight. If it's a magical tree, he may not know exactly what it needs to grow well.
One challenge could be controlling the power of the Juubi. It's an incredibly powerful and chaotic force. Naruto would have to struggle to keep it in check so that it doesn't overwhelm him and cause him to lose control. If he loses control, he could end up harming his friends and allies instead of protecting them.
One challenge could be dealing with competitors. If his company is in a competitive field like ninja training, there might be other established companies or individuals who see him as a threat and try to undermine his business.
One challenge could be the cultural shock. Naruto is used to the ways of the ninja villages, and New York has a very different culture. Another challenge might be the language barrier. He would need to communicate with people in New York, and English might not be his strong suit. Also, the different fighting styles in New York compared to his ninja skills could pose a problem.
One challenge could be that the enemy is too powerful for Naruto to defeat on his own. He might have to quickly level up his skills or find allies to help him. For instance, he might need to convince some of the more reluctant ninja in the village to join him in the fight.
One challenge Naruto might face is dealing with the physical changes in the Kyuubi. Since it's a unique situation, he may not know how to properly support the Kyuubi during the pregnancy. Another challenge could be facing the judgment of the villagers. They may be afraid or not understand what's going on and turn against Naruto.
Kawaki might resist Naruto's teachings at first. Since he has his own way of doing things, adapting to Naruto's values and training methods could be difficult. Also, the village might not fully accept Kawaki right away, and Naruto would have to fight for Kawaki to be accepted, which is a big challenge.