Giant Bowser
Giant Bowser is a minor boss that appears in Super Smash Bros. Melee and Super Smash Bros. Brawl.
In Melee
Giant Bowser appears at the end of Adventure Mode, where he is fought at Final Destination. Under most circumstances, he acts as the final boss of the mode, and defeating him allows the player to finish the mode. However, if the difficulty is set to Normal or higher and the player arrives at Final Destination within 18 minutes without using a Continue, Giant Bowser will transform into Giga Bowser upon being KO'd. From there, the player must defeat Giga Bowser to clear the mode.
As a cosmetic change, Giant Bowser uses Bowser's black palette swap if he is fought on Normal difficulty or higher.
Extra appearances by Giant Bowser include an immensely large version that appears, controlled by the player, in Event 25: Gargantuans against the computer controlled similarly-sized DK. He also reappears in Event 42: Trouble King 2, where the player, as Luigi, must KO him twice. Finally, Giant Bowser can appear in Classic Mode as a random giant opponent in stage 5. Unlike other giant opponents fought on their home stages, Giant Bowser is fought on the Fountain of Dreams stage, usually belonging to Kirby.
In Brawl
Giant Bowser makes his usual appearance on Classic Mode in Brawl as a possible giant opponent on Stage 8 (despite his frequent appearance from Melee; in both 1 player modes Classic Mode and Adventure Mode). Additionally, like in his appearance in Adventure Mode in Melee, Bowser has a chance to appear on Final Destination in Classic Mode as a random opponent on Stage 11. However, this is just normal Bowser; not Giant Bowser.
Aside from being a random giant opponent in Classic Mode on Stage 8, Giant Bowser's closest resemblance to being a minor boss like he was in Melee is in the event Event 27: Three-Beast Carnage (which is his only appearance in Brawl). He appears alongside Giant DK and a new minor boss (Giant Charizard), attacking New Pork City.