Universe 2: Other Akira Toriyama's creations
Universe 2 was the first universe discovered by (or rather, "imposed" upon) the Vargas of Universe 1, and it is by far the most divergent. Universe 2 contains the character known as Mary Sue, who is an original creation and the only character from Universe 2 who is directly related to any Dragon Ball counterparts.
In this universe, there are apparently no Z-Fighters or Z-Villains to speak of, nor Kais or Demons. Any number of things could have happened, however, perhaps the easiest rationalization is that none of those characters were born, produced, or created in this universe. Somehow, as referenced by the Vargas, this universe may have made contact with Universe 1 rather than being summoned. This reality is home to a number of magical, silly, and parodical characters based on the earlier works of Akira Toriyama such as Dr.Slump, Neko Majin Z, Dragon Quest, Toriyama's Sandland and Chrono Trigger.
"Word of God" is that there is simply no "logic" to this universe.
- Various characters from Dr Slump and Akira Toriyama's works. (Official DBM Poster of some characters from Universe 2 before Sun Wukong appeared: http://www.dragonball-multiverse.com/imgs/events/japan-expo-2010-07/Bposter-toriworld.jpg)
- Lord Slug
- Crusher Corps and Demon Clan Elites