All right, this has gotten quite silly. You do realize that using ladders would be totally impractical. You'd never get the elephants to stand still long enough for you to place them, the defenders would fight against you, and the other elephants would simply knock them to the ground. It would never work, never in a million battles.

What you need is siege towers. Roll those up in front of the elephants, have you troops on the top all run to the front at once, and topple them down upon the elephants. Now you've not only removed the riders from the elephants but you've also gotten your troops there in one go! Much better, quicker, faster, and more effectively.