One great 'ash training fanfiction' is 'Ash's Pokémon Mastery Training' which focuses on Ash undergoing intense training regimes with his Pokémon to face tougher opponents. It's really exciting as it shows new battle strategies.
Archive of Our Own (AO3) is another great place. There are many talented writers who post their Pokémon fanfictions there. The tagging system makes it easier to filter and find the specific 'ash training' fanfictions you're interested in.
Ash's training could make him more determined. He has a new purpose now, which is to show those who betrayed him that they made a mistake. This determination could be seen in his more aggressive training regime and his eagerness to take on tougher opponents. He might also become more observant. Through intense training, he learns to pick up on small details in battles and in the behavior of others, which helps him avoid future betrayals.
One key element is probably his determination. Ash is known for his never - give - up attitude. This drives him to keep trying to improve his aura skills. Another could be his experiences with Pokémon. They might be a source of inspiration or even directly contribute to his aura training.
It could be that in this fanfiction, Ash had some personal issues come up. For example, he might have received some bad news from his family back home that made him lose focus on training and eventually give it up. Another reason could be that he found a new passion or interest that diverted his attention away from training.
In the fanfiction, Ash may train his Pokémon using ancient techniques passed down in the Pokémon world. These techniques could involve special stances or chants that enhance the Pokémon's connection to their natural abilities. It makes the training more mysterious and exciting compared to the normal methods.
It can add new plot twists. Since Ash is trained in a different way, his actions and decisions will be different, which can change the direction of the story.
One possible reason could be jealousy. Maybe someone in Ash's group is jealous of his skills or popularity. For example, if there's a character who always feels overshadowed by Ash, they might betray him out of envy. Another reason could be a misunderstanding. Perhaps Ash was misinterpreted while making a crucial decision, and that led to the betrayal.
In this fanfiction, Ash's training style would likely change significantly. Since a female Pikachu might have different energy levels or responses to training stimuli. He may need to be more gentle and patient. Instead of pushing her too hard in intense physical training, he might focus more on mental training and strategy building. Also, he might need to take into account her social needs as a female Pokémon, like allowing her more time to interact with other Pokémon in a positive way during training breaks.