Balloon Mario

Balloon Mario (called Floating Power in the Super Mario 64 DS instruction manual) is a form of Mario first appearing in Super Mario World, and later appearing in Super Mario 64 DS. The former appearance required the player to get a P-Balloon, and the latter required a Power Flower.

Super Mario World
Mario or Luigi swells up like a balloon, causing him to hover in the air. They will gradually float upwards if not moved by the player, but is capable of moving in any direction for a limited amount of time. During this time, Yoshi cannot be ridden. Mario or Luigi will start to flash when the item is about to wear off, and once it does, they return to normal size and drop out of the air. The level Tubular in the Special World requires the player to continually pick up new P-Balloons to maintain flight while they make their way across the level.

If Mario or Luigi pass through a Giant Gate while under the form, they will gain a bonus Super Mushroom.

Super Mario 64 DS
The form and its effects returned in Super Mario 64 DS where, upon picking up a Power Flower, Mario would inflate like a balloon and float. The control scheme for this transformation has been changed somewhat; Mario now gradually floats downwards instead of upwards, and has to be kept in the air by tapping the jump button, similar to swimming in 2-D Mario games. Once again, he flashes when it is about to wear off and plummets when it does. The player can also automatically end the transformation at any time by Ground Pounding. Mario is the only character who is affected this way when he picks up the Power Flower.

Super Mario-Kun
Balloon Mario also appears in volume 6 of Super Mario-Kun, being featured in a single chapter. Mario, Luigi, and Yoshi are shown with these forms throughout the chapter.

Mario & Luigi: Bowser's Inside Story
Later, in Mario & Luigi: Bowser's Inside Story, Mario can walk into an air vent and become inflated. Luigi can grab onto Mario, so they can jump higher than before and slowly float down.