Well, one possibility could be that Meloetta uses its unique musical abilities to help Ash in battles. For example, it could create harmonious melodies that either soothe the wild Pokémon Ash is trying to catch or disrupt the attacks of his opponents in battles. Another aspect could be that Meloetta's presence attracts other rare Pokémon due to its alluring music, which in turn gives Ash more opportunities to encounter and befriend different Pokémon species. Also, it might share a special bond with Pikachu, as Pikachu is always at Ash's side. Their interactions could be really cute, like Meloetta creating a little concert just for Pikachu and Ash.
It would likely bring a new level of harmony (literally) to Ash's team. Since Meloetta has musical powers, it could use its melodies to boost the morale of the other Pokémon on the team. For example, before a big battle, Meloetta could sing a song that makes Pikachu feel more energetic and ready to fight.
Friendship is a very common theme. Ash is known for making friends with all kinds of Pokemon, and Meloetta is no exception. Their bond is often explored in these fanfictions.
The storyline would likely become more complex. With Meowth around, there would be a new dynamic. His loyalty would be split between Ash and his old Team Rocket pals at first. This internal conflict could drive parts of the story.
Meloetta has a musical and somewhat mysterious nature. Ash, on the other hand, is always on adventures. Combining these two elements makes for an interesting dynamic in fanfiction. Their potential relationship can bring a new angle to the Pokemon story, like Meloetta's melodies influencing Ash's battles or their emotional connection.
Meowth joining Ash in a fanfiction could also lead to some interesting character development for both. Ash might learn more about the Pokémon world from Meowth's perspective, especially the seedy side that Meowth has been a part of with Team Rocket. And Meowth could learn about friendship and loyalty in a new way, different from what he's experienced with Jessie and James.
I'm not sure specifically as 'lemon' fanfics often contain inappropriate content not suitable for general discussion. However, generally in a Pokemon fanfic involving Ash and Meloetta, it might involve their adventures together, perhaps exploring new regions, encountering other Pokemon, and forming a unique bond. But this is just speculation without knowing the exact nature of the fanfic.
Perhaps in the fanfiction, May kisses Ash as a way to thank him for always being there for her. Ash, being a bit clueless at first, is stunned but then realizes his own feelings for May. The story could then follow their journey of exploring these new - found romantic feelings while still continuing their Pokemon adventures. For example, they might have to deal with how their Pokemon react to their new relationship status.
The fanfiction could focus on Ash's daughter's relationship with her father. Ash could teach her all he knows about Pokemon battles and care. They might go on adventures together, and she could learn valuable lessons from him. For example, how to befriend wild Pokemon or how to strategize in battles. It could also show how Ash has changed as a father compared to his days as a young trainer.
One possible storyline could be that Ash, after many adventures, returns to Saffron City where Sabrina is. Their relationship could start from Ash challenging her gym again but this time they see each other in a different light. Maybe Pikachu plays a role in bringing them closer, like it gets lost in Sabrina's psychic maze and Ash has to work with Sabrina to find it. This shared experience could be the start of their romantic journey.
Well, one possibility could be that Ash's Ralts has a special ability that sets it apart from other Pokémon. Maybe it can communicate with Ash in a unique way, like through emotions. This could lead to Ash having a deeper understanding of Pokémon in general.