Cupil can morph into various shapes, and gains power by eating Chams and Abirik Chams, Moon Stone shards that are hidden throughout the game. Conversely, he will cough up all Chams and Abirik chams he has eaten if fed a Chom.
Cupil can morph into weapons and attack enemies upon fina's request. Fina never directly uses Cupil to attack, rather sending it at an opponent to morph and execute an attack on it's own. Fina can equip no other weapon besides Cupil; Cupil evolves and gains the ability to change ito a new (and usually more damaging) form. It's most powerful form is Cupil Final, although it required a download in the Dreamcast version in order to get the final cham. When not in battle, Cupil takes the form of a bracelet that Fina wears.
Ironically, or perhaps to balance out battle attributes, Cupil is the most powerful weapon in the game in his final form, despite Fina being the weakest member of the party. Cupil's forms are as follows:
- *Cupil weight awards +15 to Fina's Dodge Stat
- **Final Cupil has an attack of 300 in the Legends remake.