A fanfiction could focus on Ash Greninja's unique form and abilities. For example, it could tell a story where Ash has to rely on Greninja's special skills to overcome a powerful, mysterious Pokemon in the Alola region. This would show the significance of their partnership in the context of Pokemon Sun and Moon.
One possible fanfiction could be about Ash and Lillie's adventure in the Alola region. Maybe they team up to face a powerful new Pokemon that has been causing trouble. They use their combined skills and the unique bond they've developed throughout their journey in Pokemon Sun and Moon.
One great Ash and Serena fanfiction in the Pokemon Sun and Moon setting is 'A New Adventure Together'. It has a really engaging plot where Ash and Serena meet up again in the Alola region and go on a journey to discover new Pokemon. The author does a wonderful job of capturing their characters and the unique charm of the Alola region.
In some fanfictions, Ash Greninja's moment of saving Ash from a dangerous fall during a battle in the Alola region is really cool. It shows their loyalty and quick reflexes.
In many such fanfictions, the plot might involve Ash's friends suddenly turning against him due to some false accusations or misunderstandings. For example, they could believe that Ash has been secretly working with an enemy group, which leads to his betrayal.
One interesting story could be Ash having a unique adventure in Alola that's different from the main series. Maybe he discovers a new type of Pokémon or a hidden power within his existing Pokémon.
A fanfiction could start with Lillie having a strange dream about a legendary Pokemon. Ash believes her dream could be a sign. So they set out on a quest to find this legendary Pokemon. Along the journey, they meet different characters from the Alola region who give them clues. Their bond deepens as they face difficulties together and eventually find the legendary Pokemon, which turns out to have a special connection to Lillie.
The best aspect is seeing their relationship grow. In the Pokemon Sun and Moon setting, they get to experience new things together. For example, Serena can learn about the unique Alola Pokemon and Ash can show her around. Their interactions are really sweet, like when Ash introduces Serena to his new Alola friends. It adds a new dimension to their relationship.
Ash is the central character for sure. Then there could be some new characters created specifically for the fanfiction. They might be the ones who instigate the betrayal. For example, a mysterious trainer who has a grudge against Ash. His friends in the Alola region play a big role too. They are the ones whose reactions to the so - called betrayal by Ash form a major part of the story. Pikachu, as Ash's most loyal pokemon, is also a key character as it has to deal with the situation where Ash is being betrayed.
One common plotline is Ash's various female companions in the Pokemon Sun and Moon series forming a closer bond with him, like Lillie gradually opening up more to Ash and having adventures that bring them closer. Another could be Mallow cooking special meals for Ash, which is seen as a form of her showing her affection in the fanfiction world. Also, the idea of them all traveling together and facing challenges as a group, with Ash at the center of their little 'harem' is quite popular.