Mega Mario

Mega Mario is a form that Mario and some other characters can take by eating a Mega Mushroom or simply Super Mushrooms in many games. This form allows the players to grow into an enormous size, allowing them to destroy every enemy in their path and obliterate almost anything (including Flagpoles, Boos, and Jelectros).

Mario Party 3
In the minigame Toadstool Titan of Mario Party 3, characters could grow giant by obtaining the Mushroom hidden in one of the several Brick Blocks every round. Once the character had obtained the mushroom, he or she was capable of knocking out other characters in a short period of time. Mega characters cannot jump and control their moves, however, instead charging in whatever direction they are facing.

Mario Party 4
In Mario Party 4, the Mega Mushroom causes one to enlarge in size and hit two Dice Blocks. While Mega, the player can take 10 coins from any opponent the player squishes. The Super Mega Mushroom works the same way, but with three Dice Blocks.

Paper Mario: The Thousand-Year Door
In Paper Mario: The Thousand-Year Door, Mario or his partners can become huge by using a Power Punch. This increases their attack power briefly for a few turns. During a few Bowser intermissions, if he eats enough Meat, it has the same effect as a Mega Mushroom and makes him huge, invincible, and destructive for a brief time. Princess Peach can also swallow a potion that makes her momentarily giant, although no other effects are seen.

Super Paper Mario
In Super Paper Mario, when Mario (or Luigi, Princess Peach, or Bowser) grabs a Mega Star, he will turn 8-bit, much like his sprite from Super Mario Bros., and grows to giant proportions as well. As Mega Mario, Mario will be able to break blocks, enemies and anything in his path, much like the Mega Mario form from New Super Mario Bros.. Mega Mario and Luigi are shorter and faster, while Peach and Bowser are taller but slower. In Chapter 3-1, there is a specific Koopa Troopa that collects a Mega Star, causing it to become massive; it is known as the Mega Koopa. According to the InterNed, the music plays while one of the characters is in Mega form (including the Mega Koopa) is titled "An Unrivaled Battle".

Additionally, by feeding Princess Peach a Red Apple while she is in her comatose state, she momentarily grows to a giant size.

Super Mario 64 DS
In Super Mario 64 DS, the Super Mushroom has the same effects as the Mega Mushroom, and makes the player into a larger size. The character can then obliterate almost anything in his path, and if he breaks more than eight objects, he will get a 1-Up for every additional object he destroys. The Super Mushrooms are always found in Bricks scattered throughout the level and are introduced in Bob-omb Battlefield. The character cannot do any special types of jumps, such as the Triple Jump. If Yoshi grabs a Super Mushroom, he gains the ability to punch.

New Super Mario Bros.
The Mega Mario form returns in New Super Mario Bros., being obtained from the rare Mega Mushroom. The more objects Mega Mario breaks, the bar above his head will get filled in. If he crushes a certain amount of objects, Mega Mario can gain up to five 1-Up Mushrooms. Mega Mario also has the ability to squash any of the game's bosses in one hit, including Bowser in any of his forms. If Mega Mario falls into a pit, the purple toxic water or lava, or if time runs out, he is instantly defeated. If the Mega Mushroom is activated in tight spaces, Mario's transformation will be cancelled and the Mega Mushroom will return to the touch screen; however, if Mega Mario is crushed in any way, he will revert to Super Mario and lose a life immediately after. Additionally, if Mega Mario completes the level, he destroys the flagpole, which will fill up one-fifth of the meter above him, ensuring at least an extra life is gained. After the Mega Mushroom wears off, Mario reverts to Super Mario, regardless of whatever form he was in before using the Mega Mushroom.

The Mega Mushroom's design was originally going to be similar to that of Super Mario 64 DS ' s Super Mushroom, but was changed in the final version.

New Super Mario Bros. 2
The Mega Mario form returns in New Super Mario Bros. 2, again being obtained from the Mega Mushroom, acting the same as in the previous game. However, unlike New Super Mario Bros., Mega Mario does not gain 1-Up Mushrooms for destroying blocks. He can still knock over the Goal Pole, though, but will only receive 3 1-Ups.

Super Mario 3D World
Mega Mario appears in Super Mario 3D World, making this game the form's second appearance in a 3D Mario platform game after Super Mario 64 DS. The form functions identically to the way it does in the 2D games, allowing Mario to smash through objects and enemies. However, as Mega Mario, he can ground pound to create a shockwave that automatically defeats enemies and hits surrounding blocks.

Mario Super Sluggers
In Mario Super Sluggers, any character can become temporarily Mega by finding a Mushroom in the mini-game, Graffiti Runner. When players are giant, they can create small earthquakes that can paralyze all ground opponents for a brief period. However, they are still vulnerable to body checks, Chain Chomps, and characters that are invincible.

Mario Kart Wii
In Mario Kart Wii, Mega Mushrooms appear as items. When characters use the Mega Mushroom, they become gigantic, allowing them to squish opponents and get a speed boost. However, they are not immune to Lightning, invincible racers or Bullet Bills; Mega players hit by Lightning revert to their original size.

Mario & Luigi: Bowser's Inside Story
In Mario & Luigi: Bowser's Inside Story, one of Broque Monsieur's attacks during his battle with Bowser involves hitting a block and obtaining a Mega Mushroom. While mega, he attempts to ram Bowser, but this attack can be countered by punching him.

Mario & Sonic at the Olympic Winter Games
The Mega Mushroom appears in the DS version of Mario & Sonic at the Olympic Winter Games, in the Dream Curling event. Some of the panels appearing on the ground are Mega Mushroom panels, which cause the stone to increase in size.

Mario Tennis: Ultra Smash
In Mario Tennis: Ultra Smash, any character can temporarily transform into Mega form by picking up a Mega Mushroom the sideline Toads randomly throw onto the court. While in this form, players can hit the ball more easily.

Trivia

 * Mega Mario is similarly to the result of him drinking milk in the Got Milk? commercial of Super Mario 64.
 * A similar form to Mega Mario, though unnamed, appears in the Club Nintendo comic "Mario in Mariozilla". Kamek accidentally turns him into this state.
 * In The Super Mario Bros. Super Show! episode, Mario Meets Koop-zilla, Mario becomes Mega Mario, not by a Mega Mushroom, but by the Super Sushi. This is before Mega Mario officially appeared.
 * In Super Mario 3D World, when a character turns into their Mega form, they have scowling expressions.