If you are looking at the or XEX files for an RGH/JTAG console: Dragon Ball Z: Burst Limit
: You unlock them by completing certain requirements in the Z Chronicles story mode, such as hitting an opponent with a specific move or waiting for the timer to reach a certain point. Dragon Ball Z: Burst Limit ISO & XEX - Xbox 360...
These are collectible "items" or allies that trigger unique cutscenes during gameplay when specific conditions are met. If you are looking at the or XEX