Story-related, can't be missed.
First the baby will be shooting out little purple balls at you so you need to dodge them. After that, the baby will charge at you so you'll need to hop on the dresser and hop over baby when it comes near you, then grapple the string on his back and mash the button.
For the second wave the baby will run away and throw toys at you and dodge everything you can, it will charge at you again and you need to do the same thing you did with the string in the first wave.
The third wave has everything from waves one and two put together, but once you yank his string this time he will be defeated