ENEMY USES THESE DAMAGE TYPES:
Gist - Thermal
Guristas - Kinetic
Serpentis - Thermal/Kin
Blood Raider - Thermal
Sansha's Nation - EM
Angel Cartel - ALL
Mordus - Thermal
Sevens forces - Kinetic
Mercenary - ALL
Thukker - Explosive

ENEMY WEAK AGAINST THESE DAMAGE TYPES:
Guristas - Kinetic
Serpentis - Thermal
Mordus - Kinetic
Blood Raider - EM THermal
Sansha - EM
Angel - Explosive
Mercenary - Thermal
Rogue Drones - EM
Thukker - Thermal

*** Targeting systems ***
Minmatar - Ladar
Caldari - Gravimetric
Gallente - Magnetometric
Amarr - Radar

http://zkillboard.com/
http://www.eve-central.com/
http://eve-survival.org/wikka.php?wakka=MissionReports

Veld = 100% Trit
Scord = 67% Trit, 33% Pye
Plag = 50% Pye, 25% Trit, 25% Mex
Pyro = 82% Trit, 11% Mex, 6% Pyee, 1% Noc
Omber = 42% Trit, 42% Iso, 16% Pye
Kernite = 50% Mex, 25% Trit, 25% Iso

*** Stacking penalties ***
1 mod 100%
2 mod 86.9%
3 mod 57.1%
4 mod 28.3%
5 mod 10.6%
6 mod 3.0%