Microphone Attack

Microphone Attacks are a feature from Bloodstreams Battles: Zero Hour, Bloodstreams Battles: Zero Hour Remastered and Bloodstreams Battles Online that acts as an alternative special move button.

Zero Hour
Just make some noise into your Nintendo 3DS microphone close enough to trigger your fighter's Microphone Attack.

Zero Hour Remastered
Push the left analog stick to trigger your fighter's Microphone Attack.

Online
Just make some noise into your microphone from a USB port or laptop's built-in microphone to trigger your fighter's Microphone Attack. Note that this requires Microphone Attacks to be enabled from the Options Menu.

Trivia

 * In Zero Hour and Zero Hour Remastered, whenever you performed a Microphone Attack, a blue (red if P2) flash occurs. This effect would become dropped in the next game, however.