How do you beat the second elephant with legoas everytime I try I fail..

The Oliphaunts that require Legolas (in story mode) are not too difficult to beat.

First, shoot the Oliphaunt twice, once in each leg (on one side). It is best to try this right after the Oliphaunt turns around. Jump onto the lower arrow and swing up to the next. Reverse direction and jump to the rope. Climb up the rope and kill the the enemies (you only need to kill the main one on the platform, but it may be easier to kill the rest as well). Then run up to the front of the harness and you should see an action comand, this will have Legolas shoot the Oliphaunt in the head.

In Free Play, any character (except Gollum and the Mini Balrog, which is DLC) can do this. The character must have a bow (either theirs or a Mithril bow) and either be an Elf or be equipt with the appropriate Mithril Items (Spring Boots for jumping and Gloves for swinging). Note: You cannot equip the Mithril Gloves and a Bow at the same time, you must use the bow and then switch.