It differs from normal attacks in that it can only be used when the Special Move meter, which appears below the character's stats on screen, is filled at least once. By default, the Special Move meter only holds one charge, but can sometimes be upgraded via a character's Skill Tree. For example, Tinker Bell can upgrade her Special Move meter three times, to hold a total of four charges. The meter is filled via the use of purple Sparks.
Once the Special Move meter has a charge, the Special Move may be performed by tapping the (right bumper) on the controller; doing so will consume one charge on the Special Move meter. Each character's Special Move is unique to the character in some way.
Note: Characters from Disney Infinity 1.0 have neither Special Moves, nor a Special Move meter.
See also: Skills and Abilities