Cerberus
Non - Elemental
Cereberus is a hound from hell. When summoned his three heads combine their powers to cast Double and Triple over your party. This makes him very useful for boss fights. He is also powerful when junctioned due to his high number of abilities.
Cereberus can be found in a large concourse area in Galbadia Garden when you enter it to find Edea. There is a save spot below him. Run into him and prepare for a difficult fight. Dispel him if he casts triple on himself as with triple he is really damaging. Cast float on yourself to stop him from casting Quake on you. After this keep healing and draw triples off him to help yourself. If you beat him he will join you.