Whip from Skyward Sword.
Usable item: Allows one to strike opponents from a good distance (deals very low damage though, and never knockback) and if you try to grab while holding it, you'll be able to grab someone from very far away, or steal any items the opponent is holding, thus, swapping the whip with that item.
It has 16 uses before wearing out, after which it can only be used to deal low damage from a distance.
Kuribo's/Goomba's shoe from SMB3.
Usable item: Is automatically equipped to anyone who lands in it after jumping, allows the user to jump high and land on opponents for good damage and knockback, as well as helping them get around the stage. They can't use any regular attacks while in the shoe, and it will wear out after 20 seconds. The user is vunerable to damage, but not knockback while in the shoe. It's not possible to jump in the air, so you'll have to be careful not to fall off the stage.
However, if the user is hit by a smash attack, the shoe will be destroyed. A meteor smash or spike can also send the player falling to the ground quickly, destroying the shoe on impact.