Judging by the Farmer's dialogue, the Evil Corn appears to be a Wrath Potion-mutated regular corn cob.
As of the current version, Evil Corn does not function properly in Multiplayer. His hiding ability does not heal on hit and will instead show ridiculous healing numbers. Evil Corn will also not drop popcorn. The netcode for Evil Corn is so unstable that it will actually desync for multiple players and appear to rubber band around. With all of these ridiculous shortcomings, Evil corn becomes practically a simple miniboss in multiplayer.