Power Balloon

A Power Balloon, sometimes shortened to P Balloon or P-Balloon, is an item introduced in Super Mario World. When touched, it inflates the playable character and allows them to float through the air like a balloon.

Super Mario World / Super Mario World: Super Mario Advance 2
In Super Mario World and its remake, Power Balloons can be found in four levels: Donut Secret 1, Donut Secret 2, Forest of Illusion 1, and Tubular. The item's effect is to make whoever picks it up swell up and become Balloon Mario or Balloon Luigi, causing them to hover in the air. They will gradually float upwards if not moved by the player, but are 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 puff in and out when the item is about to wear off, and when it does they return to normal size and drop out of the air. The level Tubular in the Special Zone requires the player to continually pick up new Power Balloons to maintain flight while they make their way across the level. If Mario or Luigi pass through a Giant Gate while under the effects of the Power Balloon, they will gain a bonus Super Mushroom.

The Power Balloon in the source code of the prototypes for the original SNES game originally was going to be red before it was changed into beige in the final game.

Super Mario Maker 2
Power Balloons were added to Super Mario Maker 2 in the version 3.0.0 update released on April 22, 2020, only available in the Super Mario World style. In this game, the Power Balloon item floats in place rather than floating away to the right, and is now bright yellow rather than beige. The character's appearance also changes more drastically when obtaining the item, with Mario and Luigi's overalls and Toad and Toadette's undershirts turning yellow with a letter "P" on them (the "P" is on Toadette's dress in her case), similar to what the P-Wing does. The functionality of the Balloon form was also altered, allowing the character to be fully in control of which angle and direction they are floating towards, as opposed to the original game's simple vertical and horizontal mobility. The time limit is also removed. In the nighttime ground theme, Power Balloons fly around in circles, eventually disappearing.

Super Mario World television series
The Power Balloon made three appearances in the Super Mario World television series, most notably in the episode "Mama Luigi" where Luigi uses it to float safely down a chasm. Later in the episode, Mario uses it to re-inflate Luigi back to his normal shape after he was flattened. In the series, the Power Balloon is referred to as a magic balloon. It also appears in another episode, "Gopher Bash".

Super Mario-Kun
The Power Balloon also appears in volume 6 page 111 of Super Mario-Kun, being featured in a single chapter. It shows itself coming out of a ? Block.

Trivia

 * In Super Mario World and Super Mario World: Super Mario Advance 2, if Mario or Luigi has the powers of a Super Mushroom, Fire Flower or Cape Feather, and grabs a Power Balloon, he will still have whatever powers he originally had as well as those of the Power Balloon. However, if he collects any of these items while under the effects of a Power Balloon, the Power Balloon's power will instantly wear off.
 * In Super Mario World: Super Mario Advance 2, when Mario or Luigi grabs a Power Balloon, the music becomes slightly slower than usual. Slow music also plays in Super Mario 64 DS while Mario is under the effects of the Power Flower.