Shadow Pokemon In Essentials

I downloaded V16.2 and changed nothing except for adding Shadow Rush and the Shadow type. However, the Shadow Pokemon system still doesn't seem to work properly for me.

Specifically, whenever I go into battle with a Shadow 'mon, the normal type effectivenesses don't appear to apply. Attacks that should do x2 effectiveness to the Shadow Pokemon only cause neutral damage, and immunities yield neutral damage too. Why is this? Do I need to change something?

Also, when adding Shadow as a weakness to the Types.pbs, do dual-typed Pokemon have a x4 weakness to Shadow moves, or only a x2 weakness?

You have to edit the "Weakness"-part of the other types in the pbs file "types.txt" to affect the effectiveness of the shadow type.

I added Shadow weaknesses to the pbs file, but defensively it doesn't change anything. Shadow Pokemon still don't register appropriate type resistances and immunities when attacked.