Instructions
Engage the Nightmare SP monsters to begin the battle. Select the "Sword" icon on your battle menu with the "A" button. The Nightmare SP will only react to sword attacks, so make sure you bring your sword into each battle.
Select the "OK" option in the battle menu to begin the battle.
Line up in front of the Nightmare SP, and press the "B" button to use your sword attack.
Repeat step 3 until the Nightmare SP is defeated. The monster has 220 HP, so it may take multiple sword attacks to bring it down.