Bowser's Zero HP Glitch
From SmashWiki, the Super Smash Bros. wiki
Bowser's Zero HP Glitch (a.k.a. "Undead Bowser") allows Bowser to survive with 0 HP in a stamina match.
[edit] How to perform
While playing as Bowser in Stamina Mode, get a Smash Ball and transform into Giga Bowser. If Bowser's HP is depleted while transformed, he will instantly revert to his normal form with no hit points. Bowser can continue fighting as normal until he is hit by an attack. This is functionally no different from having 1 HP, as any attack which will cause Bowser's death would also deplete a hit point. While in this state, Bowser can be defeated by Squirtle's Water Gun or Mario's F.L.U.D.D., which normally do not deal any damage.
