Can any of Batman's gadgets knock enemies unconscious?
Off the top of my head:
- Batarang: Stun, drop weapon
- Batclaw: Disarm, and as @BlackBat reminds us, yank an enemy off a ledge.
- Cryptographic Sequencer: No combat applications.
- Disruptor: Use on a mine to KO nearby enemies.
- Explosive Gel: Stun and knock down an enemy. KO will only occur if a wall (even a weak one) explodes next to, above or below the enemy. Enemies may also be KO'ed by a non-wall blast if it knocks them off a ledge.
- Freeze Grenade/Freeze Cluster Grenade: immobilize only
- Grapnel: Upgraded Grapnel Boost will KO an enemy.
- Line Launcher: Line launcher kick will KO any enemies in the path, so will dropping down from the line for a takedown.
- Remote Batarang: Knock down stun at high speed or lock on. Getting it electrically charged first may do a knock out (I think it did in AA, I haven't tried that in AC).
- Remote Electrical Charge: Momentarily disrupts enemy, knocks down armored enemies.
- Smoke Bomb: Obscures enemy sight. Can stun a tight group of enemies.
- Sonic Batarang: Electrical discharge upgrade will KO 1 enemy equipped with a heart monitor.
The Batclaw can be used to pull enemies into walls. This can occasionally induce unconsciousness... Likewise, it can be used to pull someone off of a raised platform, causing them to fall and, depending on the height of the fall, lose consciousness. This is particularly useful when you are in cover and above someone who happens to be on a raised platform below you (like on a landing at the top of a flight of stairs).