Hardeners to use (primary/secondary):
Angels - Explosive/Kinetic
Amarr Navy - EM/Thermal (about equally)
Blood Raiders - EM/Thermal (about equally)
Caldari Navy - Thermal/Kinetic
Gallente Navy - Kinetic/Thermal
Guristas - Kinetic/Thermal
Khanid - Thermal/EM (other damage types often mixed in)
Mercenary - EM/Thermal (Kinetic missiles)
Mordus - Kinetic/Thermal
Odamian - Kinetic/Thermal
Rogue Drones - Exp/Kin with some EM (queens and rulers)
Rogue Pirate - all damage types, no clear focus
Sansha - EM/Thermal
Serpentis - Thermal/Kinetic

Main Damage type to shoot at the enemy:
Guristas - Kinetic
Serpentis - Thermal
Mordus - Thermal & Kinetic
Blood - EM & Thermal
Sansha - Thermal
Angel - Explosive
Mercenary - Thermal
Drones - EM/Thermal

-------------------

1 Burrow
2 Hideaway
3 Refuge
4 Den
5 Yard
6 Rally Point
7 Port
8 Hub
9 Haven
10 Sanctum

Hidden - Easy
Forsaken - Medium
Forlorn - Hard