Well, if Team Rocket finally got Pikachu, they'd probably first try to present it to Giovanni. They might be overjoyed at finally achieving their long - sought goal. But Pikachu would surely try to escape. Maybe Pikachu would use its electric powers to shock the Team Rocket members and make a run for it while they're dazed. It could also be that Ash and his friends would quickly come up with a rescue plan to get Pikachu back. They'd likely follow Team Rocket's trail and then stage a big battle to free Pikachu.
Pikachu would likely be very angry. It loves Ash deeply and being separated from him would make it furious. It would probably immediately start attacking Team Rocket with its electric attacks. It might also try to find a way to communicate with Ash, perhaps by using its electrical signals in a way that Ash could somehow detect from a distance.
Well, in such a fanfiction, Ash might start using Team Rocket's sneaky tactics. He could learn from them how to be more devious in catching Pokémon. For example, he might use their elaborate traps instead of his usual straightforward battles. This would be a huge change from his normal good - guy image.
Well, if Serena joins Team Rocket in a fanfiction, she might bring a new dynamic. Maybe she's forced to join at first. She could use her skills in battles and her knowledge of Pokemon to help Team Rocket in their schemes, but secretly she could be planning to take them down from the inside.
Well, if Misty joins Team Rocket in fanfiction, it would be a huge shock to the other characters. Her friends like Ash would be completely bewildered. Maybe she's been tricked into it somehow, like being deceived by Team Rocket's false promises. This could lead to some really interesting plot twists. For example, she might be used to set traps for Ash and the others, but deep down still have some good in her that causes internal conflict within Team Rocket.
They could also change Team Rocket for the better. Maybe they would introduce a new sense of honor or fairness. Ash's determination and Misty's feistiness could influence the other members to be less about pure evil and more about having fun in their villainous deeds. In a fanfiction, this could lead to some really interesting character development for both Ash, Misty and the Team Rocket crew.
Well, if Ash joined Team Rocket, he'd probably bring a whole new dynamic. His skills as a trainer could be used in unexpected ways. Maybe he'd try to reform Team Rocket from the inside, using his kind heart and love for Pokémon to change their ways. He could also introduce new strategies for capturing Pokémon that are more ethical than Team Rocket's usual methods.
One thing that would happen is that his Pokémon battles would take on a whole new meaning. Instead of battling for the sake of becoming a Pokémon master, he might be battling to further Team Rocket's goals. His Pokémon would have to adjust to this new purpose. Also, Ash would probably have to wear Team Rocket's uniform, which would be a really strange sight for fans who are used to seeing him in his normal get - up.
Well, it could make for a really interesting fanfiction. Dawn joining Team Rocket would change the whole dynamic. Her Pokémon might not be too happy about it at first. She could bring new ideas to Team Rocket, since she has a different way of thinking compared to Jessie, James and Meowth. However, it's also possible that she would secretly be working against Team Rocket from the inside, trying to take them down while pretending to be one of them.
If Team Rocket turns Ash into a Pokemon, his relationship with his old Pokemon would change. His Pokemon might not recognize him at first. But as they sense his familiar spirit, they could try to protect him. And Ash, in his new form, could learn a lot about the true nature of Pokemon. He could discover secrets about their evolution, abilities, and the hidden powers within them that he never knew as a human trainer.
The meeting could happen by chance. Maybe the reader is exploring a new area in the Pokémon world, like a forest or a cave, and stumbles upon Team Rocket in the middle of one of their schemes, like trying to steal a rare Pokémon. It's a classic way for the encounter to occur.