The Nuzlocke Challenge is a set of rules intended to create a higher level of difficulty while playing the Pokémon games. Many challengers feel that the rules also serve the purpose of encouraging the use of Pokémon the player would not normally choose, and promoting closer bonds with the player's Pokémon. The rules are not an in-game function, but are self-imposed on the part of the player, and thus subject to variation.
The Nuzlocke Challenge has only two rules that the player must follow. These are referred to as the "core" rules, and are as follows:
- Any Pokémon that faints is considered dead, and must be released or put in the Pokémon Storage System permanently (or may be migrated or transferred with Poké Transfer, as long as the Pokémon is never able to be used again during this run).
- The player may only catch the first Pokémon encountered in each area, and none else. If the first Pokémon encountered faints or flees, there are no second chances. If the first encounter in the area is a double battle, the player is free to choose which of the two Pokémon they would like to catch but may only catch one of them. This restriction does not apply to Pokémon able to be captured during static encounters, nor to Shiny Pokémon.
Other near-universally used rules include:
- The player must nickname all of their Pokémon, for the sake of forming stronger emotional bonds.
- The player may only use Pokémon they have captured themselves, meaning Pokémon acquired through trading, Mystery Gifts, etc., are prohibited. As for trading and retrading the same Pokémon (for the purpose of evolving a Graveler, for example), there is no firm consensus. As of White: Hard-Mode Episode 3, it is implied that the player can accept Pokémon that are received freely from NPCs.
- The player may not voluntarily reset and reload the game whenever things go wrong. Being able to do so would render all of the other rules pointless.
Though the above rules tend to stay consistent with all challengers, many optional variations and amendments to the rules have been created by players to further adjust difficulty. These include, but are not limited to:
- The player's Starter Pokémon must be randomly chosen using a system based on their Trainer ID number. A common system is if the last digit of the player's ID number is 1-3, the player must choose the Grass-type starter; if it is 4-6, the Fire-type starter; if it is 7-9, the Water type starter; if it is 0, free choice. Alternatively, use the Trainer ID modulo 3 for the same purposes.
- The core rules are not officially enforced until the player has gained their Poké Balls and can catch Pokémon. For example, the PoochyenaRSORAS/ZigzagoonE that the player has to save Professor Birch from is not counted as the first encounter on the route, and other encounters are not counted until the player has the ability to catch Pokémon. Likewise, in the games where the rival battle is immediately after obtaining the starter Pokémon, the "any Pokémon that faint must be released" rule is often not enforced at that time.
- Species/Dupes Clause: The player may continue fighting Pokémon in a new area until a species is encountered that has not been caught yet, which then immediately counts as the first encounter. This is to increase variety in a player's Pokémon collection.
- A limit may be set on how many times they can apply the Species/Dupes Clause in an area. If this many duplicate Pokémon are encountered in an area, the Species/Dupes Clause is no longer applied for that area and the player has to settle for the next Pokémon they encounter, regardless of its species.
- A black out/white out is considered to be a "game over," even if there are Pokémon left in the PC.
- The player is restricted to only catching the first Pokémon after each gym battle, instead of first Pokémon in each area.
- The player must use the same number of Pokémon as the opponent uses during a Gym battle or rival battle.
- The battle style must be changed to "set" in the options menu, meaning the player do not get the opportunity to switch out their Pokémon after an opponent's Pokémon faints.
- The player's Starter Pokémon must be released or permanently boxed after the first wild Pokémon is caught.
- Potions and status-healing items may not be used, so the player may only use Pokémon Centers for healing.
- Conversely, banning the use of Pokémon Centers and relying only on Potions and items for healing.
- The player is limited in their Pokémon Center visits to a certain number per town.
- Held items may not be used.
- The number of Poké Balls able to be purchased per Poké Mart is limited to a certain number.
- Master Balls may not be used.
- The player may not evolve captured Pokémon, but evolved Pokémon may be caught.
- (Black 2 and White 2 only) The difficulty must be set to Challenge Mode, which increases the levels of opposing Trainers.
- Legendary Pokémon may not be used.
- As a mercy rule, the player may have 1-3 "second chances" or revives of fallen team members.
- Shiny Clause: Shiny Pokémon do not need to be released if they faint.
- As another mercy rule, each Gym Badge may act as a checkpoint. If the player gets a game over, they may start over from when they got their previous Gym Badge.
- If the player has no Pokémon that can use a field move that is required to continue the game, they may catch another Pokémon that can learn said field move. However, it cannot be used in battle for any reason, and must be released, permanently boxed, or migrated as soon as it is no longer needed or if the player catches another Pokémon that can use said field move.
- The "first encounter only" rule is modified for within the Safari Zone. One encounter may be had for each area, or one encounter may be allowed for the entire Zone.
- Poké Marts may not be used; the only items that may be used are those found in the overworld or given to the player by NPCs.
- The player may not flee from battle.
- The Pokémon in the player's collection are limited to a certain level based on the next Gym Leader/Elite Four/Champion's highest leveled Pokémon. What to do with Pokémon that surpass this limit is up to the player.
- Poké Balls may not be used. Any Pokémon obtained must be either given to the player or hatched from an Egg.
- The Day Care may not be used.
- The Exp. Share may not be used. In Generation VI onward, it must be turned off; in Generation III and earlier, it may only be given to "dead" Pokémon.
- Quality-of-life features, such as Pokémon-Amie, the DexNav, or Super Training, may not be used.
- Online resources (walkthroughts, guides, etc.) may not be used.
Many other rules exist; challengers adjust their personal rules according to their own preferences. Any of these challenges can be considered a true Nuzlocke Challenge as long as the core are still in place.
This is a more unpredictable variant of the Nuzlocke Challenge. In this variant, any Pokémon caught must immediately be traded using Wonder Trade and the received Pokémon should be used instead. Typically this comes with a level restriction where if the received Pokémon is more than a certain number of levels higher than the original Pokémon, it must be traded again until an appropriate-level Pokémon is received.