To unlock the second voice set of Rukia, Ichigo, Renji, Byakuya, Kenpachi, you need to play through episode mode and complete all of the unlock requirements from the unlock section in the main menu or the secrets section in the extras menu depending on the version you are playing. The unlock requirement will differ depending on the character.
To unlock the third voice set of Rukia, Ichigo, Renji, Byakuya, Kenpachi, you need to clear the challenge battle of the character. Challenge battle is a battle mode where you fight the strongest version of the character, it is unlocked after completing episode mode.