Im confused by your title. Are you refusing to use Chichu or what? Regardless, Lightning is a fine replacement in the fight. The fact that you even mention Nabaat (a SAB) leads me to assume that you may not have a good understanding of the battle system or at least this particular game. Goblin Chieftan, Cloudburst, Chichu/Lightning is the preferred paradigm pack for this fight. There are other teams that will work but those 3 are by far the most foolproof. Watch this video and if you have any questions afterwards, I'll be more than happy to try to answer them.
Out of curiosity, have you done any of the other DLC?
http://etrosgate.com/ ~~~ The Gameplay Nexus for Fabula Nova Crystallis Final Fantasy
Yes. Completed all the dlc and a perfect game. Just need to beat Gilgamesh. I'm currently using lightning and a souped up ultros to test if I can keep from staggering him. Using Cerberus to deplete his health. ---lightning is hitting at 2000-3000 and Noel and serah hitting for 1500+ per hit. Of course the damage is higher as the chain increases. China Tomate Madre Foca