Literature
Pick Your Poison - Rule Set
Pokémon Red Nuzlocke, “Pick Your Poison” Rule Set
Nuzlocke Standard Rule 1 – You may only catch the first Pokémon you encounter in a new area (Caves, Forests, Oceans, Lakes, and routes after cities count as “new areas”)
Nuzlocke Standard Rule 2 – If your Pokémon reaches 0 Hit Points, you must consider it dead, and permanently store it in the box. No cheating or skimping out this time.
The Dupes Clause - Once you have caught a species of Pokémon, you may never again catch that Pokémon or any member of its evolutionary chain. (E.g. You catch Metapod; you are never able to catch Cat