Among the best defenses against a Malboro is equipping a GF with the StatDefx4 ability and junctioningPain, Confuse, Berserk, and Sleep, negating nearly all the Malboro's status abnormalities, leaving only Slow and Slow Petrify. One can also replace Berserk with Break and allow the berserked character hit away at Malboro's HP. With Auto-Haste equipped, Slow won't afflict the character, and if HP is high enough, the other attacks won't KO the party before they kill it; with the entire party thus prepared, the player could simply wait for the battle to end.
If the player hasn't got enough of above mentioned spells (or StatDefx4), they should at least junction Sleep, Berserk and Confuse, which still leaves a character available to cure the party; Selphie'sFull CureLimit Break is a quick way to cure the party from status effects, though Siren's Treatment command, Remedies and Esuna are good as well.
If the player has Ribbon, they can become invulnerable to Bad Breath. Getting a Ribbon is tough however, being a rare treasure from Chocobo World (original versions) or a rare treasure from Angelo Search (Remastered).
Equipping a character with Initiative lets them have a turn before the Malboro can use its Bad Breath. Having Quistis in critical status and ready with Degenerator will instantly defeat any Malboro. If the party is at a low level, the player may wish to use the Tonberry GF's Level Up ability to ensure a better chance of Malboro Tentacle drops.
Because of Malboro's high HP, Demi works well against it, dealing 9999 damage easily. The spell can be drawn from Malboro, making draw-casting a good strategy. The player can summon Cerberus to triple-cast Demi.
[view·edit·purge]"Malboro" may derive from the Japanese onomatopoeia boro, the sound of an upset stomach. The word mal, means something bad or illness. The name could also be a reference to Marlboro Cigarettes, since the creatures often spew horrid fumes.