In Melee, he appears as a boss. To fight him, Adventure Mode must be cleared on Normal or higher in 18 minutes or less. He will appear after Bowser is defeated. Defeating him without using a continue rewards you with the Giga Bowser trophy. He also appears in Event 51: The Showdown with Mewtwo and Ganondorf by his side. It is possible to use Giga Bowser by using an Action Replay for the Gamecube.
In Brawl, Bowser turns into him by using his Final Smash, Giga Bowser. Here, he is noticeably much larger, scarier-looking and more devastatingly powerful. He appears on the stage for about 12 seconds.
To unlock this trophy, one must defeat Giga Bowser in Adventure Mode without continuing.
An even more imposing figure than the original King of the Koopas, Giga Bowser is roughly twice the size of his scaly, fire-breathing, spike-studded, Super Smash Bros. Melee counterpart. Predictable, this monstrous creature's offensive and defensive powers are a grade higher than those of regular Bowser. Good luck defeating this colossus!
Giga Bowser is the only boss in any Smash game to have a damage meter as opposed to Hit Points. This means that simply attacking him isn't enough to KO him, he must instead be knocked off the stage.
In Melee, if a CPU Giga Bowser captures an opponent with Koopa Klaw, he can bite his opponent, but no damage will be inflicted.
There is some irony in the trophy description in Melee, as it wishes good luck in defeating Giga Bowser, even though unlocking the trophy requires beating Giga Bowser.
Among the subtle differences between Bowser and Giga Bowser is their eyes - Bowser's eyes make him look like he's concentrating, while Giga Bowser's eyes are manic-looking and somewhat bloodshot.
Giga Bowser is one of four bosses who can grab and throw players, the others being Master Hand, Crazy Hand, and Tabuu.
Giga Bowser's stance on his Melee trophy is similar to Mario's in Brawl.
Strangely, if the player views the narrator voice tracks under Melee's sound test in English, Giga Bowser's Japanese name "Giga Koopa" is announced as one of the numbered tracks. Additionally, if the player listens to this track while the language is set to Japanese, the announcer will refer to him as Giga Bowser. This is ironic due to localized names of the original bowser are swapped.
In Melee, when a CPU Giga Bowser lands or does his Giga Bowser Bomb, the player's controller will start to shake.
The word "Giga" in Giga Bowser is often parodied with a dinosaur's name-"Giga" in Giganotosaurus (a meat eating dinosaur larger than Tyrannosaurus Rex). Giga Bowser is a parody of "Giganotosaurus".
If by chance Giga Bowser gets shrunken by a Poison Mushroom, he would be slightly smaller than a normal sized Bowser.
If Giga Bowser is defeated in All star mode, he can't continue even if he has enough coins but may fall down as a Mario Trophy.
Giga Bowser will look weird if he appeared in the Game and Watch's stage.