Lol, wow, I commented on 3 of those links XD
Zozo is an internet hoax. If you check the links Linda provided I also included links to various websites explaining it's a myth. It was started in the mid 2000's and all the tales I came across were the same story, a man who was a writer spoke with Zozo then everything went downhill.
Regarding speaking with the devil, I personally do not believe in him, but your friend can call to him the same way one would call on any other deity for advice. Via a Ouija Board I'm not sure if it would work. As a child I use to be told tales of how the devil would pretend to be a spirit called 'Mr. Smiley' but like Zozo it's just a scary story. [See also saying 'Bloody Mary' in a mirror]
My question is why is your friend interested in meeting a demon or the devil? You don't need a Ouija board to contact them by the way. Research a demon thoroughly [strengths, weakness, summoning, dispelling] and try contacting it. While demons aren't evil they are very manipulative, so you shouldn't summon one for fun, make sure you or your friend does a lot of research before trying anything.