Monty Mole (4)

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

Jump up the ledges and use High Jump to reach 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, use High Jump to reach 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. This makes a bridge appear.

Cross the bridge to reach a wall with a crack in it.

Hammer the cracked wall to clear the way and go inside.

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

Jump over sparks and onto platforms to cross the area.

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