The plot twists can be really exciting in pokemon pearl tweaking fanfic. Maybe the tweaking involves changing the order of gym battles or introducing new villains. This can completely change the flow of the story and keep readers on their toes. Also, the way the fanfic might re - imagine the Pokémon world, like changing the geography of Sinnoh region slightly, can be fascinating.
First, you should have a good understanding of the original Pokémon Pearl game. Know the characters, the Pokémon, and the overall plot. Then, decide on what you want to tweak. It could be a single Pokémon's ability or the entire story arc.
Toge Inumaki is important too. His special cursed speech ability makes him stand out. Also, the principal of the school, Masamichi Yaga, is likely to be important as he is in a position of authority and has an influence on Gojo and the other students. There could be other characters like the members of different clans that also play roles in the complex web of the story.