Jusqua's Doppelganger mostly uses physical and dark-elemental attacks in battle. It has access to the spells Darkra and Darkaga. When using physical attacks, it may also inflict the Suppress and Curseailments. When it is encountered in the Witch's Mansion as a boss, the doppelganger receives higher stats and can attack twice per turn.
When fighting the enemy, it is highly advised of the player to equip a Darksteel Shield to all party members and to attack with light-elemental spells and weapons.