The Mountain

@Sunny Sunset

Spoiler

Use a sort of Ramp Climbing technique. The stair was not misplaced. You go back where you start and click as far as you can go (next to the stairs), and quickly pull up the Draggable. B will climb on it and fall farther than where you clicked. He should be past the stairs. After that, go to the other Draggable block and use the Ramp Climbing trick to win.

Spoiler: Final solution if you give up

Once you are on the other Draggable block, you need to climb. Click on the stairs near your original starting spot (next to the rails), and bring the Draggable up. B will climb to an area where it's possible to reach the win. Just click on the Win Block afterwards.