In Litwick, Lampent, and Candelure's Pokedex entries, it says that their ability can be either Flash Fire, Flame Body, or Shadow Tag as a hidden ability, but I was given a Litwick with the ability Infiltrator. Please explain?
You tagged generation 5. In Gen 5, Chandelure's hidden ability (Dream World) was Shadow Tag - it was never released, and in Gen 6, Nintendo changed into Infiltrator. I'd assume that it's still Shadow Tag because it hasn't been updated or Chandelure isn't available in Gen 6 yet?