Sneak Army

The Sneak Army (スニークアーミー) is a black version of Stealth Sneak that must be fought in the 34th and 4th seeds of the Hades Cup. Like Stealth Sneak, Sneak Army is a giant chameleon-like Heartless that's capable of turning invisible.

While it does appear in the first Kingdom Hearts, it is simply called Stealth Sneak, and is only given a name and journal entry in Kingdom Hearts Final Mix.

Strategy
Apply the same strategy as you did for Stealth Sneak, but take more caution; it tends to switch places more frequently than its predecessor, so lock on to it. You are also recommended to use Aeroga to double the damage you deal to the enemy.

The Sneak Army shoots a ball of light from its hands, and you can evade this by simply jumping. It also fires white lasers from its eyes, though they do not have homing properties. You can either stay far away from it, or attack it directly at the center of the Sneak Army's head (not the sides, because you will receive damage). Repeat these steps accordingly and you will have it down in no time.

Trivia

 * Curiously, when a Sneak Army is defeated it does not fade into darkness like other Heartless do. Instead, it collapses to the ground and twitches.