The player may not evolve their captured Pokémon, but evolved Pokémon may still be caught.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 number of Poké Balls able to be purchased per Poké Mart is limited to a certain number.The player is limited in their Pokémon Center visits to a certain number per town.Or, Pokémon Centers may not be used, meaning only Potions and items may be used for healing.Potions and status-healing items may not be used, so the player may only use Pokémon Centers for healing.
A common system is if the last digit of the player's Trainer 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.
Being able to do so would render all of the other rules pointless.
This restriction does not apply to Pokémon able to be captured during static encounters, nor to Shiny Pokémon. If the first encounter in the area is a double battle, the player is free to choose which of the two wild Pokémon they would like to catch but may only catch one of them. If the first wild Pokémon encountered faints or flees, there are no second chances.
The Nuzlocke Challenge has only two rules that must be followed: