Monty Mole (4)

Head to the area just west of the northward-bound Teehee Valley path.

Jump up the ledges and use High Jump onto the higher one in the back.

Follow the path to a gate.

Pound Luigi into the ground and have him pass under the gate.

Hit the block to open the gate.

With Mario, High Jump to the west ledge and enter that area.

Spin Jump to the southwest and west across several high platforms.

When you reach a Boo statue in the northwest area, push it with Luigi's thunder ability, stunning Mario from behind.

A bridge will appear; cross it to reach a wall with a crack in it.

Hammer the cracked wall to clear the way and enter the cave.

In the cave, pound Mario into his Mouse size and jump into the next room.

Get across the area by jumping over sparks and onto platforms.

At the end, the Monty Mole will give you the Iron Pants.