I usually do delayed mbb3 (as in hold b3, then mb it later for armour). It baits the AI pretty hard into committing into a move. For example, if you do a delayed mbb3 on batman from a certain distance, he always tries to punish with grapple. I usually cancel it into a forward dash for a full punish.
Some of the stuff the AI does is just friggin ridiculous though. I remember I was facing batman and he did a prarry right out of sweep range, so I tried to punish it. Completely forgot he had a bat out, and got baited so hard.
Also the AI reads your inputs, so just fuzzy guard. Don't do strings with gaps either, the AI will blow it up hard, or just backdash out.