The Poison step avoidance glitch occurs in Pokémon Red and Blue. Normally a poisoned Pokémon loses one HP due to poison every four steps. However, saving and resetting allows the player to reset the step counter back to the next four steps.
Additionally, use of the glitch item "il" (hex:6D) will set the number of steps remaining until poison damage to two steps.
If the player walks three steps with a party of no active Pokémon, this will result in a black out. However, the amount of steps required for a black out can be reset by saving the game and resetting.
This method allows the player to enter a Trainer battle or a wild Pokémon battle without any active Pokémon, but this will only result in a black out after the battle begins.
In Pokémon Yellow, this glitch was patched, as the game checks for fainted Pokémon every step instead of four.