Damage dealt by NPCs
Angel Cartel | Explosive/Kinetic
Amarr Navy | EM/Thermal
Ammatar Fleet | EM/Thermal
Blood Raiders | EM/Thermal
Caldari Navy | Thermal/Kinetic
Equilibrium | Thermal/Kinetic
Gallente Navy | Kinetic/Thermal
Guristas | Kinetic/Thermal
Khanid Navy | EM/Thermal
Mercenary | EM/Thermal/Kinetic/Explosive
Mordu's Legion | Kinetic/Thermal
Odamian | Kinetic/Thermal
Rogue Drones | Explosive/Kinetic/Thermal
Republic Fleet | Explosive/Kinetic
Sansha | EM/Thermal
Serpentis | Kinetic/Thermal
The Syndicate | Kinetic/Thermal
Thukker Tribe | Explosive/Kinetic

Damage to deal to NPCs
Angel Cartel | Explosive
Blood Raiders | EM/Thermal
Equilibrium | Kinetic
Guristas | Kinetic
Mercenary | Thermal
Mordu's Legion | Thermal/Kinetic
Sansha | EM/Thermal
Serpentis | Thermal/Kinetic
The Syndicate | Kinetic/Thermal
Thukker Tribe | Explosive

When in doubt, kill it with fire.
(use thermal)