The difficulty is not very high on the 30 seal orbs. I think both should be duo/trioable. The first time we tried Antagonistic it was with PLD NIN 2box WHM. It took us a bit few to figure out how to drop his defense and we were not prepared for the under 25% Gravic Horn / Quake blast spam. We timed out around 18% on that attempt.
Quake blast make it very difficult to drop him since your tp is constantly getting reset.