What is your preferred registration method?
Username + optional password and email address. First, with this option, you don't really have to create a permanent account, the site just need you to have a username, some sites will store your access for some time for you to be able to access that account using the same browser until the session expires or you've been logged out of the site. And if you want to access that account anytime, anywhere and in any device, you can just set a password (and email address for recovery purposes and other bonuses).
General signup with push e-mail verification would be my choice mate. I see some gambling required the KYC details to start the betting or other gambling services. Mostly people will be ignoring those kind of site in crypto currency invested gambling sites.
Actually it is not with the big usage if we all the details to them.
Being anonymous is the matter for bitcoin usage means you no need to give more details.
When I encounter a gambling site with complicated registration steps, I don't continue joining. You will and will always find a better site with easier method of signing up.