Unless you’re training session is specifically about using iPads or Android tablets, the best way to introduce new users to all of the Google Documents features is to have them use a browser (again Chrome is preferable) on their laptops. You can certainly have people bring their iPads and or Android tablets to your training session, but make sure that they know that not all of the features available in a desktop browser are also available in the iOS and Android apps.
When I have participants bringing iPads or Android tablets to one of my workshops, my preference is to have people try all of the features of Google Documents in their browsers before moving to their tablets. This way they have exposure to all of the functions of Google Docs. Then when they move to their tablets they can clearly see the differences between the browser experience and the tablet app experience.