I have encountered a Jigglypuff few times in the Pokémon anime. One episode in which alien Pokémons kidnapped Pikachu to power their spaceship showed Jigglypuff. Also, there were several episodes around that episode showing her. I am talking about that Jigglypuff.
Jigglypuff's singing put every sentient being to sleep (which made me wonder why she isn't the most powerful Pokémon out there) and if that wasn't enough, someone has given her a microphone which can be converted into a marker which angry Jigglypuff can use well. Who gave it to her?
I don't believe a Jigglypuff is born with a microphone. While a microphone could be of evolutionary advantage to a Jigglypuff in survival, I doubt a marker is really required. Also, I can find lots of images of Jigglypuff without a microphone.
Or, is a Jigglypuff really born with that microphone-marker thing?