Event 31: The Ultimate Bodyguard
From SmashWiki, the Super Smash Bros. wiki
The Ultimate Bodyguard (護り抜くもの, Whom you Protect) is the 31st solo event match out of a total of 41 in Super Smash Bros. Brawl. The player fights as Marth, who is against 2 Ganondorfs. Marth is also partnered with Zelda, but she will not fight; she will simply remain crouching if not attempting to recover, and the match ends in failure if the player (Marth) or Zelda is KO'd. That said, if the stage reaches its third form, she will transform into Sheik and start to fight - with surprisingly high attack power, able to KO the opposing Ganondorfs at low percents.