Evil Koaladog. It's Koaladog except it's pitch black in color and very aggresive. 2 of them would spawn in the creator boss fight. If you kill it, it becomes a normal Koaladog
So the first idea ia an enemy called a Gobblelin. It would have a baseball bat in it's hand and a large mouth. I can shoot Gobblelin-bombs from it's mouth. The bombs would explode, spawning more Gobblelins. If you kill it, it drops a baseball bat, and infanite Gobblelin-bombs