Medical attestation : if your national licence doesn’t mention it, you’ll have to show a medical attestion aged of less than one year and saying that you are able to ride a unicycle for leisure and competion.
Youngers : youngers aged less than 18 who come without their parents will have to give a parental authorization for medical and surgical interventions in case of emergency.
Fell free to send me a better translation -> cyclhop.webmaster@free.fr ;-)
How to proceed :