Typically, his old team could include Pikachu, of course. Then there might be Charizard, Bulbasaur, Squirtle, and others like Greninja. These Pokémon have been with Ash through different adventures in various regions.
They might have adventures exploring new areas in Alola that they didn't get to before. For example, finding hidden caves filled with rare Pokémon or uncovering ancient secrets about the region.
Sure. 'Ash's Alola Pokemon Team' is a fanfic that centers around exactly that. It shows how Ash assembled his team in Alola, the training they went through together, and their unique bonds. Another one is 'The Alola - bound Pokemon of Ash' which gives insights into the individual personalities of his Alola Pokemon and how they work together as a team.
Well, Ash and his Pokémon might get involved in local Alola festivals. His Pokémon could participate in Pokémon - themed contests or challenges during these festivals. Also, they might team up with local trainers and their Pokémon to protect Alola from any potential threats, like a group of wild Pokémon causing chaos in a village.
Perhaps there is a threat to Sinnoh that only Ash's old Pokémon can help solve. Some kind of ancient evil that has knowledge of Ash's past Pokémon battles. Ash and his old Pokémon then have to work together to defeat this threat. They might need to combine their old strategies with new ones they learn in Sinnoh to succeed. And along the way, Ash might meet some of his old friends who are also in Sinnoh and they help him in his mission.
It could be Pikachu. Since Pikachu has been with Ash from the very beginning and is his most iconic Pokémon. It's very likely that in Sinnoh fanfiction, Pikachu would be frequently used as it has a strong bond with Ash and is also very powerful.
A common theme in such fanfictions could be Ash's adventures in Alola while building relationships with different characters. Maybe he forms special bonds with his Pokémon and the people around him in a more romantic or friendship - deepening way.
One aspect to consider in 'Ash, Champion of Alola' fanfiction is Ash's character growth. He has come a long way from his early days in the Pokémon journey. In this Alola setting, he has to adapt to new Pokémon, new training styles, and new friends. His victory as champion is not just about battles but also about his personal development and how he has influenced the Alola region. For example, his unique bond with his Pokémon in Alola might be different from his previous regions, which can be a great focus in fanfictions.
One great 'Pokemon Ash Alola' fanfiction is 'Ash's Alolan Adventure'. It has Ash making unique friendships in Alola and facing new Pokemon challenges. The story really captures the essence of the Alola region with its beautiful descriptions.
One possible fanfiction could be about Ash bringing his Charizard to Alola for a special battle tournament. Ash and Charizard would have to adapt to the new environment and battle styles in Alola. They might face off against some of the unique Alola Pokémon and trainers, with Charizard's powerful fire - type moves being a real asset but also a challenge as they try to avoid causing too much destruction in the beautiful Alola region.