To capture an enemy, lift them with a human character and throw them into your base. Once they land in your base panel, they will fight everyone inside until subdued. However, there are three extra requirements.
1) The enemy must be at Valvatorez's level or lower.
2) Have a Discipline Room. To unlock this, lift and throw enemies three times to unlock the Senate bill. Pass this bill, then place it on the Cam-pain Board.
3) You must be able to create the enemy, both class and tier.