In the Special Pigs page, Corporal Pig is in the game, but he looks more like a Minion Pig with a Helmet. Just like the one from Where’s My Crown from Angry Birds Toons to Epic. Here’s the pic from the Special Pigs page.
^ This is just a regular Corporal Pig as a enemy, the @Agent Andrew martins was probably referring to that General/Leader Corporal Pig as a boss to a boss fight, He was referring to this Corporal Pig: