A way to develop both characters is to put them in a situation where they have to rely on a Pokemon neither of them is familiar with. They would have to learn about its abilities and nature together. This shared experience would force them to communicate better, Ash could become more empathetic towards Sabrina's more analytical approach, and Sabrina could appreciate Ash's more instinctive style of handling Pokemon.
For Ash, he could be developed by facing a situation where his usual courage and determination are not enough. Sabrina could be the one to guide him through it, making him learn new strategies and become more patient. This would add a new layer to his character.
For Ash, his character can be developed by showing his growth in understanding psychic - type Pokémon. Since Sabrina is a psychic trainer, his interactions with her can make him more aware of different strategies. For Sabrina, she can develop by becoming more empathetic. Ash's bold and sometimes reckless nature can teach her to be more open - minded. For example, Ash might introduce her to some new ways of training that she hadn't considered before.
Ash could be developed by facing a personal crisis regarding his Pokemon journey. Maya could be the one to support him and help him see things from a different perspective. In return, Maya could be put in a situation where she has to make a tough decision about her Pokemon, and Ash's advice could be crucial for her character development. They could also develop their relationship as friends, learning to trust and rely on each other more deeply.
For Ash, you could show his growth in understanding more complex Pokemon strategies, especially with Fennel's influence. Maybe he starts to take a more scientific approach to training, learning from Fennel's research.
For Ash, he could develop more patience in his Pokemon training, inspired by Lana's calm and collected nature when dealing with water - type Pokemon. Lana, on the other hand, could become more adventurous like Ash. For example, she could start to explore more terrains outside of water - related areas.
To develop their characters further, a fanfiction could put them in a situation where they have to save a group of endangered Pokemon. Ash's impulsive nature and Burgundy's more calculated approach could either clash or complement each other. Through this experience, they both learn to adapt and grow. Ash might become more patient, and Burgundy might become more open - minded, which would enhance their individual characters and their relationship.
For Ash, his character could be developed further by showing his growth in understanding different Pokemon cultures. With Molly, he could learn new ways of interacting with Pokemon that are different from what he's used to. For example, if Molly has a closer bond with water - type Pokemon due to her origin, Ash could learn from her how to better communicate with them.
Greta could be developed by exploring her backstory more. Maybe she has a special reason for being so passionate about fighting - type Pokemon. Also, her interactions with Ash could lead to her becoming more open - minded about other Pokemon types. She might start to incorporate different strategies that Ash uses into her own battling style.
One way to develop their characters further is through a story arc where they are separated from their Pokemon for a while. Ash, who is so used to having his Pokemon by his side, would have to rely on his own wits and survival skills. He might discover new strengths within himself. Lily, too, would be in a similar situation. When they reunite, they could share their experiences and have a newfound respect for each other. Also, they could get involved in a diplomatic mission in the Pokemon world, representing different regions. This would require them to be more diplomatic and understanding of different cultures, which would add new layers to their characters.
For Ash, he could be developed further by showing his growth in understanding the more delicate and nurturing aspects of Pokemon care from Erika. Maybe he starts to learn about different types of Pokemon food and habitats that Erika is an expert in. For Erika, she could be shown to become more adventurous like Ash, willing to step out of her comfort zone of her garden. For example, she could join Ash on one of his more daring quests.
For Ash, he could develop further by learning some of Domino's more strategic ways of battling. This would make him a more well - rounded trainer. Domino, on the other hand, could learn from Ash's unwavering determination and bond with his Pokemon.