Game NPCs

When it comes to writing a story about a video game like Pokémon you can run into some issues like established Game NPCs. In certain cases, not much modification needs to be done to the characters such as Wigglytuff in the PMD games. But for others, like many of the gym leaders and rivals in Rising Smoke, major modifications needed to be made based on the setting. In some cases NPCs are even replaced entirely just for simplicity's sake. So what do you think? Should NPCs be replaced, stay the same, or just undergo modifications to fit the story's need?

It really depends on the nature of the story itself. In my case, I just gave them a unique little encounter based on where you would find them in the game, to keep the story from sounding like a monster parade.