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.
The player's Starter Pokémon must be released or permanently put into a PC box after the first wild Pokémon is caught.The battle style must be changed to "set" in the options menu, meaning the player does not get the opportunity to switch out their Pokémon after an opponent's Pokémon faints.The player must use the same number of Pokémon as the opponent uses during a Gym battle or rival battle.
The player may only catch the first Pokémon after each Gym battle instead of in each area.A black out/white out is considered to be a "game over," even if there are usable Pokémon left in the PC, and the player must start over.Alternatively, use the Trainer ID modulo 3 for the same purposes.
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.
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.