Maybe an older priest who has a long - time companion Pokemon, like a Growlithe. He uses his experience with both the church and Pokemon to guide the younger members of the congregation, especially those who are also trainers. He helps them see how their Pokemon can be a part of their faith and not just for battling or collecting.
One possible plot could be a group of Pokemon trainers who are also devout church - goers. They use their Pokemon to help with community service around the church, like using water - type Pokemon to water the church gardens. Their Pokemon also play a role in the church's events, such as Pikachu using its electricity to light up the church during a special evening service in a power outage.
It could also be a new character created specifically for the fanfic. A young girl who has a natural gift for music and can communicate with Pokemon through melodies. She might use her talent to solve problems in the Pokemon world, like helping Pokemon that have lost their way or are in distress because of some dark force that is disrupting the natural harmony of the Pokemon world.
I'm not sure exactly as it depends on the specific 'the challenger pokemon fanfic'. But usually, there would be a young and ambitious Pokemon trainer as the main character. This trainer would be eager to prove themselves in the Pokemon world.
There might also be a villain who wants to use the power of fennel - influenced Pokemon for their own gain. This character would add conflict to the story and be a major antagonist for the other main characters to face.
Since we don't know the exact details of 'the gathering pokemon fanfic', the main characters could be a group of young and enthusiastic Pokémon trainers. They might be on a journey to become the best and this gathering could be a crucial part of their adventure. It could also feature some Pokémon with special personalities as sort of secondary main characters, like a Pikachu that has a unique ability compared to others. Another possibility is that there are some wise old Pokémon trainers who are the main characters, guiding the younger ones during the gathering.
It could be Pikachu as a main character. Since Pikachu is one of the most popular Pokémon, it would be likely to be involved in the story, perhaps bouncing on the trampoline and having a great time.
Obviously, Cheryl is one of the main characters. She's the center of the fanfic's story. Depending on the plot, her Pokemon would also be important characters. For example, if she has a Pikachu, that Pikachu would play a role in her adventures.
The main characters could be a group of trainers. Each trainer might have their own unique Pokemon and goals.
Perhaps an older, experienced trainer who has retired from competitive battles and now spends their time with their most loyal Pokemon. They could be living in a small cottage near a Pokemon sanctuary, and they often have visits from other trainers and Pokemon. Their story could be about sharing wisdom and enjoying the simple pleasures of the Pokemon world with their Pokemon companions.
It could be trainers. Since they are the ones who usually interact with Pokémon, they might be in the front line during the invasion.