The default badges are what are seen on regular Wiki's. All you can really do with them is rename them and change the image, nothing else.
What I have done, is created two custom tracks. This allows the creation of new badges. The Tracks I have created so far apply to the Star Wars category, and the World War II category.
To earn these badges, you simply have to lots of edits in those categories.
I am simply testing out this feature, to see whether custom tracks would work for this wiki.
Of course, they wont be for specific things like Star Wars and WW2 Games, but for broader subjects, such as Homebrew, Consoles and Mods.
When I feel the time is right to begin proper work on custom tracks, I will disable the tracks for these badges, as they are experimental. You will keep your badges, but they will no longer be earnable.