There should only be three races per faction, the Alliance should only have humans, dwarves and elves as per standard good fantasy races. The Horde being the evil faction shall have the evil races those being orcs, trolls, and the undead. From these races the allied races can come. The many various tribes and groups of dwarves and trolls. The clans/kingdoms of orcs/humans, and varied variety of elf races that are shaped by their culture and surroundings. The undead will mostly be human or elf, although a abomination style ghoul made up of other races might be acceptable.