Naruto's character could develop a new sense of curiosity. Summoning Pokemon would expose him to a whole new world of creatures and powers. He might become more adaptable as he has to learn how to work with Pokemon, which have different personalities and abilities compared to the summons he's used to in his own world.
Naruto might also become more empathetic. Pokemon are often shown to have strong emotions and bonds with their trainers. As he forms relationships with the Pokemon he summons, he'll learn to understand their feelings better. This could translate into him being more in tune with the emotions of those around him in his own ninja world, whether it's his friends, allies, or even his enemies. He could start to see the similarities between the Pokemon and the people he knows, leading to a more well - rounded and understanding character.