One of the PowerPuff girls biggest rivals/foes were the Rowdyruff Boys. The Rowdyruff Boys appear to have the same powers and strengths that the Powerpuff girls. So what was the origin of the Rowdyruff Boys?
The initial 'recipe' came from Professor Utonium himself, who saw no problem giving away the secret to the most powerful creations the world had ever seen over the phone, but the more 'manly' replacement for Sugar, Spice, and Everything Nice was Snips, Snails, and Puppy Dog Tails. These ingredients were taken from the Nursery rhyme "What are little boys made of?".
The replacement for Chemical X, which MoJo JoJo lacked in prison, was black slime found on a prison toilet.