Some of them can have two possible abilities, but they can only have one at a time.
Let's say in the case of PIkachu in this mod, it can have either Static or Lightningrod, but not both at the same time.
The critical hit damage modifier is 1.5x damage, at the same critical rate. It was a change made in Gen 6. As for that Marowak and Ninetales you mentioned, those are the Alolan Forms present in Pokemon Sun and Moon, with changed typings. Ninetales is Ice/Fairy, Marowak is Fire/Ghost.