Environment

Starfinder encounters are more likely to occur in environments with effects like radioactivity that most Pathfinder creatures were never designed to interact with. If your encounter takes place in space, the creatures and NPCs need armor with environmental protections or the cosmic trait to survive. If your encounter uses radiation, the creature should have it listed as an immunity, have a resistance to poison damage, or have the assumed damage and sickened conditions built into their stat block in advance so you don't need to apply it during the encounter.

Creatures inhabiting starships should have some way to survive. If intelligent, they should have a useful skill like Computers or Crafting. More feral creatures might inhabit vents or trash compactors and could have an ability like compression or a garbage spew ranged attack that helps make the creature more thematically appropriate. Likewise, creatures adapted to new worlds should have abilities that allow them to not only survive but thrive on those worlds in one or more ecological niches. A fast and easy way to approach adaptation is to look for another creature from the same world in Alien Core and skim its stat block for any abilities that help it survive the challenges of its home. For example, creatures from space usually have the cosmic trait and some resistance to cold damage, representing their ability to survive in the void.