Use of Elephants?

[K]

Don't forget that units with less than 5 members checks morale every turn, and due to the crazy cost of elephants most people use less than 5 at a time. Even then, unit losses take a unit below 5 and then trouble starts.

Run a test game and watch how just adding even some slingers or militia keeps your elephants in the battle longer.

The final answer really is high morale units to make a high average morale, but in most situations your "morale solution" for yout troops will vary on race and circumstances. Casting Beserker on a few elephants generally makes the whole unit unbreakable.