Instructions
Go to the parallel world "Another World" and travel to the top of Fossil Valley. You will find "Heavy Skull" there. Take the skull to the top-right house in Termina and talk to all of the inhabitants there, one of whom will be Skelly's grandmother. The skull, Skelly, then remembers his identity. Next, travel to Shadow Forest and head into the waterfall cave. Search through the notebook that you find there to gain "Angry Scapula."
Travel to Guldove and speak to the trader there to acquire "Pelvic Bone." Journey to the Hydra Marshes to gather "Good Backbone," and then to Water Dragon Isle. While in Water Dragon Isle, speak to the man standing beside the waterfall. Travel to the Isle of the Damned and head to the top left or northwest corner. Explore in this area until you uncover "Mixed Bones."
Visit Termina and speak to Skelly's grandparents there after you have assembled all of his bones. Speak to Skelly, and you will find that his memories have returned. In order to gain Skelly's special attack, you may want to travel to the Home World and travel to Termina. Once you get Serge again in the storyline, speak to the Termina barkeeper to get Skelly's attack, "OnARoll."