One interesting plot point could be Greninja's reunion with its trainer. Maybe after a long separation, there are new challenges they face together in the Alola region. Another could be Greninja's unique abilities being put to the test against new and powerful Pokemon in Sun and Moon.
In the 'pokemon sun and moon greninja returns fanfic', a possible plot point could be Greninja's struggle to adapt to the new environment of Alola. The Alola region has different ecosystems and Pokemon cultures compared to where Greninja was before. This could lead to interesting interactions with local Pokemon and trainers. Greninja might also have to learn new battle techniques to keep up with the local battle styles.
One idea could be that Greninja returns with a new power that it gained during its time away. It could use this power to help Ash in a crucial battle in the Alola region. For example, it might have learned to control water in a more unique way, like creating ice sculptures that can attack opponents.
Obviously, Greninja is one of the main characters as the title suggests its return. The trainer who was associated with Greninja before would also be a main character. They are likely to be central to the story's development.
A new Team Rocket - like organization could be the main antagonist. They might be after Greninja because of its unique abilities. They could try to capture Greninja to use its power for their own evil purposes, like taking over the Alola region.
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.
A good Greninja fanfiction in the Pokemon Sun and Moon universe often has well - developed characters. Greninja itself should have a distinct personality, not just be a copy of what we see in the games. The author should give it more depth, like its thoughts, feelings, and relationships with other characters.
The 'alola greninja returns fanfic' might focus on Greninja's journey back to Alola. It could start with Greninja feeling a pull towards Alola, perhaps due to some unfinished business or a connection it still has with the place. Once there, it could encounter various Pokemon and trainers. There might be a story arc about Greninja finding its place again in Alola, dealing with changes that have occurred since it was last there, and forging new relationships while also rekindling old ones.
Well, in this fanfiction, Lillie's return often brings new adventures. Maybe she comes back with new Pokemon skills or knowledge. It could also lead to reunions with old friends in the Pokemon Sun and Moon universe.
You could write a fanfic where the main character is a Pokemon ranger in the Alola region. They are tasked with protecting a special area that is home to a group of endangered Pokemon. Along the way, they meet various trainers and have to deal with poachers trying to capture these precious Pokemon.
You could write a fanfic about a group of friends who all start their Pokemon journey in Alola at the same time. Each of them has a different goal and Pokemon type preference. As they progress through their journey, they face various challenges together and sometimes separately. Their relationships are tested and strengthened as they deal with difficult situations like facing off against powerful wild Pokemon or rival trainers.
One interesting plot could be about a trainer who discovers a rare and powerful Pokemon in the Alola region that no one has ever seen before. This Pokemon has unique abilities that the trainer must learn to master in order to compete in the island challenges.