You grab using R2 and push enemies onto anything like off a ledge into electronics or onto walls. And you can parry incoming attacks with circle or instead dodge them using X. But if you parry on time, the enemy becomes dazed and you can perform an instant takedown with the X and square together. You can also use R2 to quick throw random objects at enemies. Square is a regular punch, but if you hold square, you can kick enemies and break their defense, but hold square with R2 to ram your body on