Before you field your companies, you can agree as a group to allow climbing. Mobile frames can gain benefit from climbing onto structures if they're at least 6 bricks high and at least 4 studs in area. When a mobile frame moves, climbing up or down 6 bricks' height counts the same as moving 1 ruler unit horizontally.
Of course you need terrain to use this optional rule. Build several pieces that provide elevation.
To climb, a mobile frame has to have at least one appropriate movement system. A mobile frame with no movement systems can climb stairs or a ladder, if it’s built into the structure.
A higher mobile frame is in cover to all lower mobile frames. A lower mobile frame is out of cover to any higher mobile frames, unless it’s under a roof. Mobile frames at the same elevation determine cover normally. Don’t consider elevation differences less than 6 bricks.
If a mobile frame falls — for instance if the structure it stood on is destroyed — it could take damage. Roll 1 damage die for every 3 bricks' height the frame fell, and use the damage chart for hand to hand attacks.