As far as I understand this, the only predefined group is "Others" as there are all things are not part of another group. Maybe "Home" also is different a bit, but you can disable "Home" also by removing it from the "Groups" definition in the XML file. The group "Others" you can't remove from being shown. But that's the one and only only group that is always there, no matter what you do in the XML file.I'm just not sure how I can add a predefined group.
If you want a new Group "Games" as a default group for your skin, you can simply add this group to the default xml file and you are good to go. All tiles needed to be defined as part of a group in the xml file. If not, all of them are shown in "Others" only. So the new Group Games is not different to any other group like Videohub or TV....
If you can give me a png and tell me where you want to have the group placed (e.g. between News and pictures) then I can make a new "default" XML with the Emulators Plugin as a tile for you to add to the next release of BV.
Edit:
Another difference between "Others" and the rest is, you can not define the grid position and size of a tile here. It always is 1x1 and the tiles are placed one next to each other...