A whole list can be seen here.
Box's can contain items, and even other boxes.
This will create a small black hole that will start eating some of the stage and characters. Lasts about 5 seconds.
Bullet BoB Blaster
Fires three Bullet BoBs, which causes 60 damage to happen to whoever get hit.
There are three different berries, the Jellatin, the Robot, and the Uranium berries. Each changes the properties of the character you playing as, for the good or bad.
Mr. Sew'n Shell
This shell will keep the character that has been hit sewn to the ground, unable to move.
Phony Celestial Crowbar
Allows the character to use a weak verison of the Celestial Crowbar that Maion can use.
When dropped, an enemy from the story mode will appear.
When thrown, it will create a platform. It uses different gravity then the required one and stepping off results in death. It will wear-off after 30 seconds.
Grants 30 seconds of invincibilty. This doesn't permit you from falling off of edges.
Makes the character so drunk he can't fight. Lasts 30 seconds.
Maya, the Angel Gaurdian
Cuases Maya, the Angel Gaurdian of Doodleland, to rescue you from falling off or getting knocked off. She only works once though.
Neo Geo Pocket Theo
Boosts attacks and is worn like a badge. Will fall off after breaking or 30 seconds.
Warps the opponent off the stage. Results in mostly One-Hit KOs.
Berries and Fruit
Heals a bit of damage, but not much.
They will stick to the players feet if you step on them, causing you to trip until they fall off. Because of the fact that they only fit the feet of Stalmers.
Allows flight for a short time (45 seconds). Used in the Story Mode a lot in Maion's stages.
Can be used by a character to enter a small dimensional box. It lasts for 30 seconds and can avoid all damage, but characters using it cannot attack from inside.
Unlocked once beaten in story mode. Allows the character to control a stongly armored tank, with even stronger blows.
Elements of Harmony
The Elements of Harmony, which are unlocked after unlocking Twilight Sparkle. They are said to be the most powerful magic known to ponydom, and perhaps in the multi-verse itself. They emit large amounts of power and will shoot beams and balls of light around the user for 30 seconds before blasting away from the user. Anyone who touches these beams and light balls will get 25 damage and will get knocked back a bit.
When touched, this will cause the user to grow twice their size and will make their attacks much more powerful. They become a lot heavier as well, and will decrease knockback by 2. It also makes the user much faster. It lasts 30 seconds.
This item requires that Mario be unlocked.
The Fire Flower will make the user have a redish tint and will now have the ability to throw two fire balls at once. These fire balls can be charged, each stage of charging can deal more damage. The Fire Flower also has fire resistance, which means that the user can go into lava and deal with fire without getting damaged. It lasts for 30 seconds.
Requires unlocking Mario.