For all the strengths that Elephants possess, I have found out that they drop like flies when you get them to rout.

I use them myself alot, but I always make sure I have a cav unit following them.
A kind of one two punch combo. Charge with the elephants keep them movng in the same direction then follow in with a cav charge. I just punch a line right through the enemies lines.

Divide and Conquer