Mimics, or ???, are enemies in Final Fantasy X found in the Omega Ruins. They are named so for their behavior of mimicking treasure chests and the shapes of fiends they take on. There are four different shapes of the Mimic, each one having a different set of strengths and weaknesses. When encountering them in a battle (always with a Zaurus), they will show up in the form of a treasure chest.
The player must steal from it (not mug, as it will destroy the chest), and if there is nothing to steal, it will change into one of the four types of Mimics, a fiendish look-alike from a pile of bones, rocks, and other debris. The party is unable to escape from the battle once they have changed into their fiend-like shapes.
Mimics are one of the best sources of gil with each one dropping 50,000 gil, double that if a party member has the weapon ability Gillionaire.
Mimic (1): Takes on the shape of Ruminant fiends. Has the highest Strength and HP out of the four shapes. Both physical and magic attacks will work, as both defensive stats are low.
Mimic (2): This one is in the shape of Mech machina. Has the lowest Strength out of all the shapes, but good Defense, Magic Defense, and the highest Speed. Using either physical or magic attacks against it will work.
Mimic (3): This Mimic is in the shape of the large Roc fiends. Has the highest Defense out of all the shapes but low Magic Defense, so magic is best used on it.
Mimic (4): In the shape of the Basilisk fiends. Highest Magic Defense, but low Defense, so it is best beaten down with weapons.