The new superboss is (SPOILER)Lost Babil. It's a failed prototype of the Giant of Babil
that went berserk after completion. The battle consists of three parts (chest, head, core), and you need to construct three parties as a result. To face him, you need to go to ??? on the moon, talk to a purple Namingway (you can also apparently talk to one of the Namingways here and do Challenge Dungeons, so they're no longer lost forevers like in the Phone and Wiiware versions), pay him 500,000 gil, and you get 3 Silver Apples and 2 Soma Drops for winning all three fights (as well as whatever experience and gil the boss parts give). There's a youtube video of it here.

Though the maker of the youtube video said that the battle is rather easy, I think they did that because they want to account for the fact that most people won't have 15 well trained characters, since it's not as important to train all your characters as it in, say FFVI.