Well, Naruto would be the central and most interesting character for sure. His unique ninja abilities would blend in an interesting way with Pokemon training. But I think Kakashi would also be great. He could use his Sharingan to analyze Pokemon battles better. And his lazy - but - actually - super - skilled attitude would be fun to see in the Pokemon world. As for the legendary Pokemon, Dialga could be really interesting. With its power over time, it could create some really cool storylines when interacting with Naruto and the others.
In this kind of fanfiction, Naruto is a must - have interesting character. His ability to make friends quickly could lead to some great relationships with different Pokemon. Then there's Jiraiya. He could be an interesting addition as he might be interested in studying the Pokemon and their abilities. He could use his toad summons in combination with Pokemon in battles. Also, the legendary Pokemon such as Rayquaza would be very engaging. It could be seen as a powerful and mysterious being that Naruto has to earn the trust of.
One possible plot for this fanfiction is that Naruto is transported to the Pokemon universe while on a mission. There, he discovers he has an affinity for training legendary Pokemon. He meets Pikachu first and they form a bond. As he travels, he encounters legendary Pokemon like Articuno. He uses his Naruto - style combat skills to earn the respect of these Pokemon. Eventually, he has to face a powerful villain who wants to use the power of the legendary Pokemon for evil. Naruto, with his new Pokemon friends, battles to save both worlds.
In a fanfiction where Naruto becomes a Pokemon Trainer, he would bring a whole new dynamic to the Pokemon world. Naruto is used to facing tough opponents in the ninja world, and he would apply that experience in the Pokemon battles. He would be fearless in exploring new areas to find rare Pokemon. His loud and energetic personality would attract a diverse range of Pokemon. His training methods might be unorthodox, but they would likely be effective. For instance, he could use his shadow clone jutsu to train multiple Pokemon at once, just like how he uses it for his own training in the ninja world.
Articuno, Zapdos, and Moltres are quite common. Their elemental powers and the mystery surrounding them make for great fanfiction material. Ash might encounter them during his travels and have to either help them or face off against them in some way.
Arceus is quite popular. Given that it's considered the creator of the Pokemon universe in the official lore, it often has a significant role in fanfictions. Mewtwo is also very common. Its powerful psychic abilities and complex backstory make it a favorite for fanfic writers to explore. Another popular one is Lugia. With its majestic appearance and its connection to the sea, it's often a central figure in many stories.
I think Mewtwo would be the most fascinating for Naruto to talk to. Mewtwo is a very intelligent and powerful Pokemon. It has complex thoughts about its existence and purpose. Naruto, with his own struggles and growth in the ninja world, could have deep philosophical discussions with Mewtwo. They could exchange ideas about power, identity, and what it means to be different in their respective worlds.
Mewtwo is also very popular. Given its origin as a genetically - engineered Pokemon, a human could interact with it in many ways. Maybe a human scientist wants to study Mewtwo further, or a young trainer tries to befriend Mewtwo and help it come to terms with its existence and powers.
Sasuke could be a very interesting character in this crossover. He has his own dark and brooding nature. He might be more interested in the stronger and rarer Pokemon. His sharingan could give him an edge in understanding Pokemon's abilities and behaviors. He could also train Pokemon in a more intense and strict way compared to other trainers.
The main character is usually a young and aspiring Pokemon trainer. There are also often strict but kind teachers who guide the students. And of course, there are the rivals, other students who are competitive and constantly challenging the main character.
Naruto is known for his optimism and that would play a great part in his Pokemon Trainer journey. When his Pokemon are feeling down after a loss, he would cheer them up. His outgoing nature would help him make friends in the Pokemon world who could give him tips on training and new places to explore. His never - say - die attitude would ensure he always tries new strategies in battles, not being afraid to experiment.
Obviously, Ash is one of the main characters. Since it's about him being a legendary Pokemon in this fanfiction, he's central to the story.