Heals like Cupcakes or Happy Jam 2 are recommended. Mega Bite deals a great amount of damage, and he uses Mega Bite more often then Toxic Bite. Consistently healing with a leveled up party is recommended.Although the fight is difficult, certain strategies can help. Phantom Puppet's fight is a pretty difficult fight, with Nightmare using Mega Bite and Toxic Bite during his fight. He could be found to the right of the Lilygear Lake entrance if you were to continue going right instead of entering the area. Nightmare can only be fought after talking to Snowcone. He also lacks the transparency his core version has, as well as the black stripe that appears on his hat. His eyelids appear to be lowered, giving him an angry look. Like many of the other nightmares, he has claws and tears on his body.
Nightmare looks almost identical to his core series counterpart, but smaller and glossier, with the fur colored black, the bowtie and hat colored yellow, and the stomach, along with the inside of his ears, colored grey.