Our strategy for Poached Eggs level 3-6 is to loft the Yellow bird over the two carts, through the solitary wooden block. This will result in the bird popping most of the pigs on the ground. Fire the next Yellow bird head-on into the stone cart, causing the wheels to rotate clockwise. The remaining pigs will be popped when the wooden cart topples. The score in the video below is 64,320.
Note: The second train in the video below is wood. On some platforms, and in older versions of the app, the train is stone.