His plan was to fight the Romans. He should have been more careful. First step would have been to destroy Pergamon. Then either befriend Makedonia or enslave them. Then the rest of Greece. Then tackle Roma. I am pretty certain that Romani would send legions after legions, but with his Mikrasian flanks secure, Antiochos could probably beat them.

As it were, the way the situation unfolded, Antiochos kept trying to field a good enough force to fight the Romani, they were one step ahead, and when actually managing to field a great force that would have defeated them, the decision to emply scythed chariots destroyed his left flank and ultimately his army, whereas he along with his Kataphracts, destroyed a roman legion and almost captured the Roman camp.

All in all, he didn't have a good strategy. If I were in his place and was planing to fight the Romans this is what I would have done.