NPC Damage types
Angel: All types, although mostly kinetic and explosive.
Amarr Navy: EM and therm
Ammatar Navy: EM and therm
Blood: EM and therm
Caldari Navy: Kin and therm
Centii: EM and therm
Coreli: Kin and therm
Corpii: EM and therm
Domination: All types, mostly kin and expl
Gallente Navy: EM and therm
Gist: All types, mostly kin and exp
Gurista: Kin and therm
Khanid: EM and therm
Mercenary: All type.
Mordus: Kin and therm
Odamian: Kin and therm
Pith: Kin and therm
Rogue drones: All types.
Republic fleet: All types, mostly kin and exp
Sansha: EM and therm
Serpentis: Kin and therm

Main Damage types to use on npc factions:

Guristas - Kinetic
Serpentis - Therm
Mordus - Therm & Kinetic
Blood - EM & Therm
Sansha - EM & Therm
Angel - Explosive
Mercenary - Therm
Corpum - EM
Seven(Zazzmatazz) - Therm