i've heard about it, it's just a myth used to scare people. while a Ouija Board is a powerful tool, our subconscious mind can play tricks with us and unknowingly move the planchette ourselves and make up stories like Zozo to frighten us. same goes with who you work the board with, they could mess with it to scare you. i've used the Ouija board a couple times over the years, and usually i just speak with the same couple spirits, i've never encountered a Zozo, but i have met a couple angry spirits, and i have learned that spirits do lie, some just want to scare you, so if you ask them if you're Zozo, they might say yes because either they think you want to speak with Zozo and they're lonely, or they see you're scared and want to play a prank for fun.
when i was a kid my friend use to play with Ouija Boards [i was scared of them most of my life so i didn't use one until i was 16 and even then i was worried] she use to tell everyone stories about the Ouija Board and she said the devil communicates through them, but he uses the code name Mr. Smiley, so if you were ever using the board and a ghost called himself Mr. Smiley, it was the devil and you needed to stop immediately, go outside, spin around 3 times clockwise, throw salt over both shoulders and say a chant. [can't remember the chant exactly] my point is people lie, spirits lie, i've never come across a Zozo personally [nor a Mr. Smiley] as long as you use the board correctly you should be fine.