It's possible that Greninja's return is part of a prophecy in the Alola region. The local people might see Greninja as a sign of great change or a hero. So Ash and Greninja have to work together not just to battle but also to fulfill this prophecy, which could involve saving the Alola region's natural balance or something similar.
The fanfiction might explore the emotional bond between Ash and Greninja in more depth. Maybe Greninja had to overcome great difficulties to return to Ash, and this journey of reunion can be full of emotions. Also, the interactions between Greninja and Ash's new Alola Pokémon friends can add a lot of fun and unexpected twists to the story.
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, it could vary a great deal. In some 'ash greninja returns fanfiction', it might focus on Ash and Greninja reuniting after a long separation. Maybe Greninja has been in a far - off place training or on a mission, and now it comes back to Ash to help him in a big battle. They then team up again, with Greninja using its unique Water - Shuriken and other moves to take on powerful opponents.
It could be that Ash has a special mission given to him by a Pokémon deity or an important figure in the Pokémon world. The mission is to bring a specific set of Pokémon to Alola for some ecological or cultural reason. Maybe there are certain Pokémon that can help balance the ecosystem in Alola, like Pokémon that can control overgrown plants or deal with an overpopulation of certain species.
Well, perhaps Greninja will encounter some new and strange Pokémon in Alola that it has never seen before. Ash could use this opportunity to train Greninja further, and they might participate in some Alola - specific Pokémon contests or battles together. Greninja's presence could also stir up some friendly rivalries among the local Pokémon and trainers, leading to exciting adventures and growth for both Ash and Greninja.
In this fanfiction, Greninja might come back with new powers. Maybe it has been on a special training journey and returns to Ash to help him in a big battle.
Well, in Alola, the battle environment is different. Ash Greninja has to adapt to the new battle rules like Z - Moves. It may start by observing local battles and learning from them. It could also adapt to the more friendly and less intense battle atmosphere compared to other regions. This means it might have to change its battle strategy a bit, not always going all - out from the start. And it might interact with different types of Pokemon that are native to Alola, which could lead to new friendships or rivalries, further shaping its adaptation to the Alola environment.
There could be unfinished business between them. They might have a shared goal that they haven't achieved yet. Greninja's return to Ash in the fanfiction could be to finally complete that goal, whether it's winning a particular Pokemon tournament or saving a certain place from destruction.
In fanfiction, Ash and Greninja might have all kinds of adventures in Alola. They could encounter new Pokémon species that are unique to Alola. Greninja could show off its skills in the new environment, impressing the local trainers. Maybe they'll participate in the Alola Pokémon League together and face strong opponents.
In this fanfiction, Ash might introduce Greninja to his family. His mother could be surprised but also happy to see such a unique Pokémon. Maybe Greninja would show off some of its cool moves in the backyard.