Hope this helps you!
Enemies ------- Hardener to use ---------Damage type to use
Amarr---------- EM/Thermal ------------EM or Thermal
Blood Raider ---- EM/Thermal -------------EM
Sanshas ------- EM/Thermal -------------EM
Caldari. -------- KInetic/Thermal --------- Kinetic or Thermal
Guristas ------- Kinetic/Thermal --------- Kinetic
Mordus -------- Kinetic/Thermal ----------Kinetic
Sanshas ------- EM/Thermal ------------ EM
Serpentis ------ Thermal/Kinetic --------- Kinetic
Minmatar. ------ Explosive/Kinetic -------- Thermal
Angel. --------- Explosive/Thermal ------- Explosive
Rogue Drones --- All Resis (pri. Expl. Therm) - EM
Mercenary ------ All Resis (pri. EM, Kinetic) -- Thermal/EM
Morduh -------- Kinetic/Thermal -----
Seven's -------- All Resis -------------- Thermal

Drones
Hornet--- Kinetic
Acolyte--- EM
Warrior--- Explosive
Hobgoblin--- Thermal