ZERO DIVIDE UNLOCKABLES
Unlock Zulu
By playing through the whole game and defeat him with all eight characters. The announcer will say "Wow" at the title screen after the last character defeats him. Zulu will be available for selection after the game starts.
Fight against Xtal
Finish the whole game without continuing using all eight characters (including Zulu).
Unlock Xtal
Finish the whole game without continuing under or normal or hard difficulty levels and defeat Xtal.
Unlock Neco
Finish the whole game as Zulu and Xtal under normal or hard difficulty level without continuing.