You could try this.
However I did have evil civs colonizing quite fine in a number of games, although they sometimes do seem to take a bit more time to do so.
Maybe they just ended up with bad starting positions?
It's been happening in every game I start, so I don't think it's bad starting positions; unless they've really been consistantly unlucky. Maybe The Drengin and The Korath are only suppose to colonise the one other planet in their homeworld system, and then get other planets solely through conquest. The problem with this theory is that, with only two planets, by the time they start attacking civs with nine or more planets -they'll be unable to compete, even militarily.
by the way: I'm playing with a gigantic galaxy, with all 9 civilizations enabled. Planets and stars are set to uncommon; so on average each civ should have about 5 or 6 planets. But the Drengin and Korath always have just two, The Yor usually get three and the Thalan and Altarian usually have about nine or ten. I wouldn't want every AI to have the same amount of planets, as that would be boring. But two AIs only having two planets, seems like it could really upset the balance. Other that this problem, I'm really enjoying my current campaign; so I'm wondering if I could somehow fix this problem in mid-game, without having to start over and to assign generics personalities to the Drengin and Korath.