The Left Orb changes color from blue, to yellow, to red. As stated by NORG in the beginning of the battle, the Left Orb will use powerful magic like Tornado and Bio when red. However, a simple attack on the Orb will turn it blue again.
The Orbs can never be destroyed, and have massive Defense that renders even the most powerful attacks weak—even the Lion HeartLimit Break, which normally does several thousand damage a hit—will only do a few hundred damage to the Orbs. Even if the player does reduce its HP to 0, it will simply regenerate.