What jobs do the rest of your group go on? It should be no difficulty to clear with MNK THF WHM and you shouldn't be afraid to sub /WAR and let the THF DD on the boss as well. Save Formless Strikes for when the PDT gets high.
I'm usually tri-boxing mnk thf whm. I do let the thf swing away for the most part but pull off when theres gonna be AoE's from hell because im not the best multiboxer. That is also why i went /nin. I usually do go /war for cerby cause he isnt that hard to tank.
I've been starting BR2 again for marduk plans and haven't really noticed much difference on Cerb (except you can't use counterstance for ***because of their increased potential to one shot you post atk/def update, same for acroliths.)
I used my eva build and with /nin i had no troubles with counterstance up on cerby. the acroliths did stomp me pretty hard towards the end of them. I'll try canceling counterstance next time never really thought of that lol.
Random Question while im in here. if i VS with 300tp then pop hundred fists and formless, does that ODD work for formless?