Walkthrough: After defeating Ghetsis and heading into the Preservation Room, you will find Giovanni as well as an unconscious Lusamine. Giovanni tells how he is using his power to control Lusamine to his will, hoping to create an army of Ultra Beasts in order to conquer all universes. He then gives you the chance to join him, only to deny your answer. He then challenges you, stating how it makes him feel oddly nostalgic about something.
Team Rainbow Rocket Giovanni - Level 68 Dugtrio, Level 68 Nidoking, Level 68 Nidoqueen, Level 68 Rhyperior, Level 70 Mega Mewtwo X