Quote Originally Posted by Squid
They are still available in a handfull of regions, you probably just haven't got there yet.

Was able to use Mercenary War Elephants in my campaign against Carthage, also had lost 3/4's of one of my legions fighting off 2 armies that had 4 Mercenary War Elephant units between them. You can get them no problem, you just have to be in the right regions to get them.