That's a good question.
Speculation:
For Humanoid races, I think it will depend on the entries. I don't think we'll get a hobgoblin minion, but the kobolds obviously will.
We know there's a Human Commoner figure, so presumably there's a human commoner entry. For orc and the other humanoid races, I'd default to the lowest level entry of that race. Thus, a kobold minion is the default kobold, while for gnolls, it is the gnoll huntmaster.
If there are two characters of the same level, default to the non-leader/non-elite version and then default to the one with the lowest HP.
For other monsters, like the grell and the grick which only have two entries, just pick the standard (lower level) version.