Vladitor can be unlocked if you beat 2 times the character, he later redeems himself and becomes a playable Bakugan.
Despite being the antagonist, Vladitor is not evil, he made a change of heart when he rescue Leonidas from dying by giving his remaining powers to him, thus earning his redemption with a positive energy in him. Despite being arrogant towards the Brawlers, Vladitor is a good Bakugan who redeems himself by saving Leonidas from death by giving his remaining powers to him before fading away in the process, leaving his partner Marduk sad and depressed from the loss of his partner Bakugan.
The player went on the same park when he meets Leonidas, Leonidas reappears to reunite with his partner, he explains to him that Vladitor saved his life from death by giving the remaining powers to him.
Vladitor has still Marduk as his partner. In fact, Vladitor survives, giving Leonidas a second chance during his redemption.