One-time use Items are hidden in ?-Blocks, most of the times at secret places. You can only hold one of these items with you.
Temporarily grows you to immense size and lets you walk over the battle field crushing any enemies on your path. Enemies with more health will just be thrown back by the stomps and not be crushed. You can't perform any attacks during the duration of this item. You still can receive damage.
With the Metal Box on you won't flail from attacks (you won't be knocked back). You can always continue combo's but will receive the damage, although the damage is always reduced. Like always you will be a tad slower than usual. There is a chance that certain characters become a different metal.
When the Super Star is activated you will be invincible for a certain amount of time. You can do anything you always do, but won't receive any damage. You can still receive knockback though. It is the rarest of the three to appear.
Healing Items often appear in ?-Blocks and even in Brick Blocks or other things you can get coins out of or from. The Mushroom and Syrup items come in Normal (which is the default name), Super, Ultra and Max. The latter one restores the status completely.
Restores your health.
Restores your mana.
Adds another life to you.
Rare heal item that restores both health and mana to its fullest.