Capturing is done by Lifting an enemy unit and Throwing it onto your Base panel.

This causes the enemy to battle all units not yet on the field. If it wins, all your units are knocked out and the base panel is destroyed. If it loses, it and all its items join your party.

The downsides to this:

  • Any units of yours the thrown enemy kills count as ally kills.
  • This new unit is not a student of one of your preexisting units, like if you simply created them as a new character.
  • You might not get experience for defeating them.

Damaging an enemy before throwing them onto the panel may help. The likelihood of subduing them appears to be based on their HP.

Depleting the SP of a monster may also help.

This tactic apparently works best in Monster units. Humanoid units are supposedly harder to subdue.

It may also not work against a unit you have not unlocked yet. If they could not be bought for mana they may not be capturable.

In Disgaea 5: Alliance of Vengeance, there is a Capture squad that can be formed in order to let your units capture enemy units through a specific move on the battlefield. This method does not require you to throw the enemy you want to capture into the base panel.