https://www.youtube.com/watch?v=MaL-66nHN9c

Amarr Empire: 50% Em, 50% Thermal
Angel: 70% Explosive, 20% Kinetic, 10% EM
Blood Raider: 50% EM, 50% Thermal
Caldari State: 50% Kinetic, 50% Thermal
EoM: 75% Kinetic, 25% Thermal
Gallente Federation: 50% Kinetic, 40% Thermal, 10% EM
Gurista: 75% Kinetic, 25% Thermal
Mercenaries: 50% Thermal, 30% Kinetic, 10% Explosive, 10% EM
Minmatar Republic: 50% Explosive, 20% EM, 20% Kinetic, 10% Thermal
Sansha: 50% Em, 50% Thermal
Serpentis: 50% Kinetic, 50% Thermal
Rogue Drones: 70% Explosive, 20% Kinetic, 10% Thermal

Rats are weak against:

Amarr Empire: EM
Angel: Explosive
Blood Raiders: EM
Caldari State: Kinetic
Gallente Federation: Kinetic
Gurista: Kine

Stacking Penalties:
Module #1 applies 100% of bonus.
Module #2 applies 87% of bonus.
Module #3 applies 57% of bonus.
Module #4 applies 28% of bonus.
Module #5 applies 11% of bonus.