Spin Smash

Spin Smash is a Badge in Paper Mario. It can be bought from Rowf's Badge Shop for seventy-five coins. If Mario equips the Badge, a new move called Spin Smash can be used. It is a hammer attack that costs two FP to perform. It behaves like a standard hammer attack and deals the same damage as one, but if the action command is timed correctly, the targeted enemy is sent flying back into all of the enemies behind them, dealing one point of damage to them. Even if only one enemy is in battle, they are still sent flying back if they are hit. Spin Smash has effects on certain enemies such as: In Paper Mario: The Thousand-Year Door, the badge is replaced by the Super Hammer, an upgrade to Mario's regular hammer.
 * Knocking off body segments from Pokeys and Pokey Mummies
 * Knocking off Shy Stacks one by one
 * Causing coins to fall from Kent C. Koopa in his flipped state

Merluvlee's prediction

 * "I see...a Spin Smash Badge. It is for sale at the open-air shop in the plaza outside the castle gate."