Twilight would be excited to explore a new fictional universe. She'd start taking notes on the magic systems and different worlds in the fanfiction. Rainbow Dash would be bored if there wasn't enough action. She'd be looking for epic battles and heroic deeds. Pinkie Pie would love the fanfiction just for the fun of it, no matter what it was about.
In fanfiction, the reactions in the Pokemon world to FLIM from MLP would be diverse. The Pokemon that are friendly and trusting, like Eevee, might initially be drawn to FLIM. However, as they get to know him better, they might realize his true nature. The villains in the Pokemon world, like Team Rocket, might see FLIM as either a competitor or a potential tool. They could try to use his skills for their own evil plans. Meanwhile, the regular citizens of the Pokemon world, such as the people in the various towns, would be cautious. They have a peaceful life, and FLIM's arrival with his business - minded and sometimes sneaky ways could disrupt their normal routine. So they would keep an eye on him to make sure he doesn't cause any problems.
Twilight Sparkle would probably be devastated. She looked up to Celestia as a mentor, so she might go into a state of deep mourning at first. But then, she could be motivated to try and fill the void Celestia left, using all the knowledge Celestia had imparted to her.
Some MLP fans might be really into it. They'll enjoy the new and different story - telling style compared to MLP. Others might be a bit confused at first, since DBZ is so different in terms of genre. But overall, a good portion of them could end up finding it interesting.
Some fanfictions might depict the MLP being excited. They could see the human as a novelty, something completely different from what they're used to in Equestria. They might immediately start asking questions, like where the human came from and what their world is like.
Twilight would be devastated. She might go into a state of shock at first. Then she could become very withdrawn, shutting herself away in her library to grieve. Eventually, she would probably turn her grief into a determination to uphold her brother's values and use her magic to protect Equestria even more vigilantly.
Rarity would be more interested in how the power levels are presented visually. If there are any shiny or impressive displays of power, she would be all about it. Pinkie Pie would just turn it into a game, making up her own power levels for the Mane 6 and seeing how they stack up against the Dragon Ball characters. Applejack would think the power levels are a bit over - the - top but would respect the fact that it's part of the Dragon Ball world.
After the initial shock and sadness, Twilight often becomes determined. She decides that she will not let the betrayal break her. In a story where she is abandoned in a dangerous realm, she uses her magic and wits to find her way back and also to expose those who betrayed her, showing that she is stronger than they thought.
The ponies' reactions would vary greatly. Rarity might be fascinated by Optimus Prime's design and might even try to make some sort of fashionable accessory inspired by him. Applejack would be more practical and would wonder what he was doing in Equestria and if he had any good intentions. Optimus would see the ponies as a new and interesting species. He would be patient with their initial wariness of him and would try to show them that he means no harm. He might also be a bit taken aback by their colorful and somewhat chaotic world compared to the more structured world of the Autobots.
The MLP franchise is aimed at a wide range of audiences including children. So, stories with erotic content are completely unacceptable as they violate the spirit of the brand which is to promote positive social and moral values.