How do you get slaves?

[Braskan, the Void's Tear]

So Ive tried to invade planets and take slaves but my armys never capture and pops

[Mr.Person]

capturing pops from bombardment is only possible with the unity trait "Nihilistic aquisition" iirc

Other than that the only way I know of is to invade and actually conquer the planet, make the pops slave status, and spread them around your systems to populate as slaves.

[Cryten]

or as a barbaric despoiler. but yes the main method is to conquer a planet then go the specifies rights and set the new species you have added to your empire as slaves.

[Oubley]

I think it also depends on your policy settings, i think you have to have the policy set to allow slaves, which means you have to be a xenophobe trait or fanatic xenophobe. If you conquer a planet and it becomes a core and if your policy is to not allow non ethnic in your cores you'll begin to purge and migrate the pops if they aren't slaves.

[Jewbacca]

Xenophobe, or Authoritarian civic.

Nihilistic Aquisition ascention, or Barbaric Despoiler civic allows "raid" bombardment stance. It starts slowly, but once pops start getting taken it becomes faster as devastation goes up.

Another method is to conquer a planet, go species tab, make sure the race is enslaved. Slaves have limited jobs they can take. The best way to use them is to resettle to your own planets, and use them in your mines, servants, and farms while your free pop goes into specialist jobs. Servants are quite useful. Giving amenities from the big nothing.