The current pre-release of the client ("pioneer" in the version) is only compatible to itself. So you can only play with other testers. Please be aware!
Looking at the code, for each army, the game tries to create 'INITIAL' group. If the group exists, that's what you get. If it doesn't exists or is empty, then the ACU is spawned.
Any other group has to be spawned by map script.
