From Nintendo Everything's Interview:
Tsuda: In the earlier days of Gunvolt 2’s development, we originally going to make Copen the only playable character, with a mask-wearing Gunvolt appearing as the new top dog of the Sumeragi Group (the evil organization from Gunvolt 1). He would be in the game as a boss character, appearing before Copen in mid-air surrounded by 1000 Glaives that he would use to transform. If you beat Gunvolt, he would be unlocked as a playable character, but due to varying circumstances we changed things to what you see in the game now.Man, how about that? All said and done, though, I'm happy that they decided to keep GV as a playable character. That said, I gotta say that I still am a little bummed that that masked GV design didn't end up used in the full game. Woulda been cool!
Anyway, you can check out Nintendo Everything's full interview with Inti Creates here! Hope you enjoy it as much as I did!