Bouncy Wario[1][2], also known as Bouncing Wario[3] and Spring Wario[4][5], is one of Wario's transformations in the Wario Land series of games. If hit by the hammer of a Pogo Guy, Hammer-bot and Menhanmā, or a hammer after it loses its spikes, Wario will be squashed and his legs turn into springs, only to spring right back up again in this state, used to spring to new heights. In all three versions, Wario has a time limit before he will return to normal (hitting a spike will also work). However, in Wario Land II and 3, pressing will let Wario jump slightly higher, while in Wario Land 4, pressing will cause Wario to jump up until he hits an obstacle, allowing him to return to normal. When the time limit runs out, Wario will bounce one final time in the direction that he last moved.
Bouncy Wario has appeared in volume 28 of Super Mario-Kun. During a fight with Spoiled Rotten, when Wario is low on health, Arewo Shitain-hakase gives Hoggus a hammer. Hoggus then uses the hammer to hit Wario, transforming Wario into Bouncy Wario. Bouncy Wario then proceeds to defeat Spoiled Rotten. Wario also uses this form to defeat Golden Diva.
^Wario Land 4 European instruction booklet, page 22.
^Brady, Matthew K., Nathan Beittenmiller, Debra McBride, and David Cassady. Game Boy Game Secrets, 2001 Edition Prima's Official Strategy Guide. Page 95.