Nightmare Mode is an extra difficulty level first introduced in Skylanders: Giants. It is considered to be the hardest difficuly level in the Skylanders console games. Only when you complete story mode do you gain access to Nightmare Mode.
After completing Nightmare Mode for either Giants, Swap Force, or Trap Team, you unlock the following hats: Knight Helm (Giants), Volcano Hat (Swap Force), and the Rainbow Hat (Trap Team).
Trivia
In Giants and Trap Team, the Nightmare Mode becomes a permanent difficulty once it has been selected. But in Swap Force, it is a temporary difficulty choice.
In Superchargers,you get Nightmare Mode straight from the box.
Nightmare is commonly symbolized by Kaos, but in Superchargers,it is symbolized by the Sky Eater.
