The Final Melee is an Adventure based on SSBM's Adventure Mode. Though it is very different from it, it is based on it.
The story begins in a cave, Mario defeated Bowser last 3 months ago. At the beginning you see Mario running from 42 Dry Bones. Luigi is held hostage by them. The enemies threaten to kill him, unless Mario will give the Power Star of Mastery, Giving them the power to take over the ENTIRE Mushroom Kingdom. After Mario warped out of the cave, He suddenly sees a letter on the ground it says:Dear Mario, I have Princess Peach with me, and without Luigi you will not be able to defeat me. Best luck trying to beat me! - Bowser Mario then set off to defeat him all before Brawl.