At the very outset, apologies for the delayed response.
I use Waze Groups to have a badge on my Waze Avatar.
The main purpose of Groups in the app AFAIK is
1. to help groups of Wazers who commute between fixed locations in the city. That way, they get traffic reports which pop up, from their group, as soon as a group member places a report on the map.(Settings-> Social Networks-> Groups).
2. for users who have to commute through known traffic bottlenecks within the city.
When I was in Bangalore, I created a Group called Waze Bikers, but it does not show up when I search for it, here in Chennai. I believe that Groups have been designed by Waze to help, groups of users within cities, and not on a National scale. I've had to create a new Group for each city of India I've stayed in.
Over the last six months, I have noticed that newbie users, cannot joining groups, which are created in another part of the country. The main reason I discovered, was the problem of them not being to join my main group even though the badge shows on my profile. This problem has been reported to support and I'm hoping Waze are able to change the initial plan they had for Groups.