Amy

The third Poe Sister you fight in the Forest Temple. In her room is a giant picture of herself. Shoot the picture to make it burn up and have five blocks fall from the ceiling. Every block except one has a section of the picture that you just destroyed, so that means that you have to move the blocks to form the face. The puzzle will be timed and if you don't finish the puzzle, the blocks will go up into the air and flip around, thus restarting the entire puzzle. The good news is that the time will be extended so no matter how bad you are at puzzles, you will finish it. Once the puzzle is finished, Amy will finally show up. If you z-target her, she'll disappear, but she'll eventually show herself again. Stay close to her and sidestep around her or use your shield if she tries to attack. Once defeated, she will disappear and the green/yellow flame will be lit.

Majora's Mask
Amy made a cameo appearance at Ikana Canyon where you can battle all four of the Poe Sisters to earn a Piece of Heart in a small hut for 30 Rupees.