There is no pork in Skittles or any other animal derived ingredients.
Skittles used to contain gelatin which was derived from pig bones so they used to contain pork but now Skittles has changed their formula.
The main ingredients in Skittles are artificial additives and colored sugars with no animal products.
Special edition flavors of Skittles might contain some ingredients that are not found in the original varieties.
In many other candy though gelatin is found in many chewy candies other than skittles.
Gelatin is made from animal bones, animal connective tissues and animal skin.
Skittles also contain palm kernel oil which many vegans choose to avoid due to it being linked to destruction of rain forest.
In short Skittles no longer contain any pork or pork or animal derived ingredients.
The main ingredients in Skittles are various flavorings and coloring's, hydrogenated palm kernel oil, corn syrup and sugar.