One of those items is the Iron Boots - but where are they located?
How To Find The Iron Boots In Paper Mario: The Origami King
The Iron Boots can be found in item boxes around the world and can also be bought.
You can find a pair in an item box floating above the ground in Picnic Road on the path below the Monty Mole stand.
But you need to use these items sparingly as they will only work for a certain number of times.
Be sure to use them only when necessary.