Normal: "A hideous fiend whose Really Bad Breath makes a regular Malboro's breath seem like Potpourri. It remains relatively unknown due to its lonely existence on the Farplane." Oversoul: "Despised enough to begin with, it's sunk to new lows in its oversouled state. Now its gastric juices can even consume items." — Scan
The Great Malboro is an enemy in Final Fantasy X-2. They are extremely dangerous enemies that should be dealt with by equipping as many status-resistant abilities as possible (Ribbon being the key accessory to use) to avoid its status-inducing Bad Breath and Really Bad Breath attacks.
It is also wise to quickly eliminate it if it Oversouls in order to prevent losing valuable items as it can quickly wear away at Eye Drops, Holy Waters, Antidotes, and Remedies. Quick and powerful classes such as Gunner and Berserker help with dealing with these enemies, as do powerful magic classes such as Gun Mage. Having an Alchemist in the party is highly recommended, as it will not destroy items if there is an Alchemist present, and it allows infinite access to Remedies if the player needs to cure statuses. They normally appear alone.