Hardeners to use
Angel - Exp/EM/Kin
Amarr Navy - EM/Thermal
Gurista, Mordus, Gallente - Kinetic/Thermal
Sansha - EM/Thermal
Serpentis - Kinetic/Thermal
Mercenary - EM/Thermal/ (Kinetic (missiles)

Key - NPC name: Damage Type it uses (Damage to use against it)
Angel Kinetic/Explosive (Explosive)
Amarr Navy EM/Thermal (Thermal)
Blood Raiders EM/Thermal (EM)
Caldari Kinetic/Thermal (Thermal / Kinetic for Temuras)
Concord EM/All Dmg Types (Thermal)
Gallente Kinetic/Thermal (Thermal)
Guristas Kinetic/Thermal (Kinetic)
Khanid EM/Thermal (Thermal)
Minmatar Fleet Thermal/Exp (Thermal / Exp for Darkanas)
Mercenary EM/Thermal/Kinetic (Thermal)
Mordus Kinetic/Thermal (Kinetic)
Odamian Kinetic/Thermal
Drones - all Dmg types (EM)
Rogue Pirate EM/Explosive/Kinetic
Sansha EM/Thermal (EM)
Serpentis Kinetic/Thermal (Thermal)
Zazzmatazz All Dmg types (Thermal)

-Smallest to Largest Site
Burrow > Hideaway > Refuge > Rally Point > Den