Spinning Kong
The Spinning Kong is Donkey Kong's Up B move. In terms of vertical recovery, this move goes a very short distance, but it goes almost as far horizontally as Meta Knight's Mach Tornado, making it a fairly effective recovery move. When used on the ground, the Spinning Kong can be used in a fashion similar to Bowser's Whirling Fortress; it can be used out of the shield, or as a disruptive tactic. The Spinning Kong's first hit, in which Donkey Kong extends his fist to charge up the spin, has decent knockback. The Spinning Kong can also act as a pseudo shield for some projectiles which is helpful when recovering.
The Spinning Kong does up to 36% damage, making it the second strongest up special in the game if all hits connect, following Lucas in first with PK Thunder 2 which can do 43%. In Brawl, the grounded version grants Super Armor just before hitting the opponent and Donkey Kong falls on his back after finishing the move, leaving him vulnerable for a moment. There is also a glitch which if he leaves the ground when using the grounded version, the Super Armor lasts for the entire move.
Origin
The moves seems to be unique to the Super Smash Bros. series. However, in Donkey Kong Country 2, Dixie Kong had the ability to spin to slow down her descent and cross large distances horizontally. Spinning Kong may have been loosely based on this move. The only difference beetween the moves is that Donkey Kong uses his arms to hover, while Dixie Kong used her ponytail. Tiny Kong later had a similar spinning move in Donkey Kong 64. However, Spinning Kong first appeared in the original Super Smash Bros., which precedes Donkey Kong 64's release.