You can only catch the very first wild Pokémon you encounter in each new route or area. If it faints or runs away, you get nothing for that route.
If you are new to Nuzlockes, stick to the vanilla Fire Red experience. Use the mGBA emulator and play the standard game. The emotional weight of losing a nicknamed starter to a critical hit is all the "mod" you need.
FireRed is widely considered the best game for a beginner’s first Nuzlocke. The encounter variety is predictable, the mechanics are straightforward, and the game lacks the complex physical/special split introduced in Generation IV. However, underestimate Kanto at your own peril. The Starter Choice: Who is Best?
Q: What is the Nuzlocke Challenge? A: The Nuzlocke Challenge is a self-imposed set of rules that make the Pokémon games more challenging.
