The "Sadistic" trait is set to do extra damage to any target that is not flagged as Advent, alien, or robotic. It also has a blacklist of enemy types that are excluded (like the lost and psi zombies). Generally speaking, enemy mods are automatically excluded, soldier race mods are included, and 3rd party factions could be either.

3rd party faction mods that WILL trigger "Sadistic" by default, but can be disabled in the config

• Bandit raiders
  
• SCP: Chaos Insurgency
  
• SCP: Global Occult Coalition (except for robotic units)
  
• Rogue XCom (except for SHIVs)
  
• SCP: Mobile Task Forces (except for robotic units)

3rd party faction mods that default to not trigger "Sadistic", but can be enabled in the config

• Black Legion
  
• Cult of Jariah
  
• Marauders
  
• Nightsisters (although the Rancor units will still not trigger the trait)
  
• Phantoms

Mods with lost and/or zombies known (or already configured) to not trigger "Sadistic"

• World War L
  
• A Better Advent
  
• Corrupt Avatar
  
• Advent Warlock (by Ashlynne_Lee)

3rd party faction mods that won't trigger "Sadistic"

• Cerberus Raiders
  
• Dark Eldar raiders
  
• Heretic Geth
  
• Hutt cartel
  
• Mandalorian faction (except for the medic probe droid, which will be affected)
  
• MOCX
  
• Robotic Raider Faction

3rd party faction mods that default to have a mix of enabled and disabled units, set to all disabled in the config

• Reapers & Collectors
  
• Terminus Mercenaries