Meowth in Team Rocket has a sad story mainly because of his unrequited love for a female Meowth. He learned to speak human language in the hope of impressing her, but she still rejected him. This made him feel very sad and lonely, yet he continues his journey with Team Rocket.
If Ash catches Meowth in the fanfiction, it would be a huge blow to Team Rocket. Meowth is the translator for their Pokémon, so without it, they would have a hard time communicating their plans to their Pokémon. This could lead to a lot of failed missions.
One sad Meowth story could be that Meowth was in love with a female Meowth. But she rejected him because he could speak human language which made him different. He was left all alone, feeling heartbroken and out of place in his own kind's community.
Another reason could be unrequited love. As I mentioned before, if Meowth has feelings for another but is rejected, that's very painful. It can lead to a long - lasting sadness.
I'm not sure specifically what the 'rocket sad story' is without more context. It could be about a rocket launch that failed, perhaps with the loss of a valuable payload or the end of an important space mission.
One reason could be unrequited love. In the Pokemon world, Meowth has a soft spot for certain Pokemon, like the Skitty. If in a fanfiction, Skitty rejected Meowth's advances, it would make him sad. Another could be his longing for acceptance. Meowth is a part of Team Rocket, but often they don't fully appreciate his skills. He might feel sad and underappreciated in a fanfiction scenario. Also, memories of his past life on the streets, before joining Team Rocket, might haunt him and bring about sadness.
Yes, in some Team Rocket fanfictions, Ash can be depicted in various ways that might involve him having some sort of connection to Pokémon in a different light. Maybe he could be experimented on by Team Rocket to gain Pokémon - like abilities, or be transformed into a Pokémon - like being in a very creative and out - of - the - box fanfiction concept.
Rocket Raccoon has a sad story. He was created through cruel experiments. He was taken from his home and turned into a weapon or tool by those unethical scientists. He was alone in a world that saw him as a freak. His only friends were those he found along his adventures like the Guardians of the Galaxy, but the memories of his past torment still haunt him.
Maybe there's a rogue Pokemon trainer. This trainer is jealous of Dawn's skills and the attention she gets. When Dawn joins Team Rocket, this trainer sees it as a chance to expose her as a fraud. He or she then tries to stop Dawn and Team Rocket's activities, thinking that they are up to no good, which they are, but the trainer has his own self - centered motives.