An awake Silcoon affected by Nightmare
The Nightmare glitch is a glitch in Pokémon Ruby and Sapphire. If a sleeping Pokémon under the effect of Nightmare has its sleep status cured by the ability Shed Skin, the Nightmare effects will remain until the Pokémon faints.
If the Pokémon is put to sleep again and is awakened thanks to Shed Skin, the glitch will persist, but if the Pokémon is put to sleep again and wakes up without Shed Skin, the Nightmare effects will go away.
It was fixed in Pokémon FireRed and LeafGreen, where Pokémon with Hypnosis and Nightmare are available without trading. It was also fixed in Pokémon Emerald.
- A Pokémon knowing Nightmare and a sleep inducing move.
- An enemy with the ability Shed Skin.
- Go to Petalburg Woods and enter a battle against a Silcoon or Cascoon, which have the ability Shed Skin.
- Put the Pokémon to sleep, and use Nightmare.
- Keep doing the above steps until the Pokémon is awakened by Shed Skin under Nightmare effects.
It is still unknown if this glitch occurs in Link Battles between Ruby and Sapphire or Ruby/Sapphire and another, newer Generation III game.