The Advent Loyalist Titan has an ability that gives it a chance to capture enemy ships whenever it fires its weapons, and they also have a tech that gives them a chance to capture fleeing enemy ships. The Rebels also have a tech that gives them a chance to resurrect their defeated enemies to fight for them, but it doesn't work at the moment. And the ultimate ability on the Rapture battle cruiser has always had the ability to capture enemy frigates since the start of Sins.