Unlock All Characters
On the Select Mode screen, choose "Group," then select "Special Brawl." A menu of options will appear. Turn on "Stamina" mode and "Flower Head" mode and press "Start." On the character selection screen, set "Player 2" to "CPU." Select "CPU Lv" and set to "PUNY." Select "Stamina 150" and set to 1. Set "Player 1 and 2" to "Random character." From the Stage Select menu, choose "Random." When the battle begins, the CPU character will instantly be defeated, finishing the match. Repeatedly hit "Start" to begin another match. Continue this for about 90 minutes or 450 battles to unlock all characters.
Unlock All Stage Builder Items
Select "Vault" from the main menu, then "Stage Builder." Select "Create New Stage" and then save each stage after building. Once you have 15 stages (the three sample stages do not count; your total count should be 18) you can either play 10 traditional battles or follow similar instructions to unlocking the characters. Be sure that when battling, you select one of your custom stages.
Unlock Stickers and Music
With all the pieces unlocked, create a stage that has a base with two columns on either side. On the top of the columns should be conveyer belts turning into the base of your structure. At the base should be three more conveyer belts all turning toward the left. Somewhere along the inside of one of the columns, there needs to be a platform a character could stand on. Once complete, save your new stage and go back to the main menu. Select "Group" and then "Rules." In the rules options, change "Rules" from "Time" to "Stock," then choose "Item Switch." Set the "All" switch to "Off," then change the sandbag to "On." Set the frequency at the top of the menu to "High." Go back to the Brawl menu and choose "Brawl." Select Kirby, activate a Player 2 and choose your custom stage.
Once the battle begins, have Player 2 stand on the platform. With your main character, stand on the bottom left-hand side of the structure and wait for the sandbags to fall. Perform the quick attack as the sandbags come towards you. This will knock out stickers and CDs consistently, eventually unlocking all these items.
Play as Zero Suit Samus or Sheik
To play as Zero Suit Samus, hold down "R" (or the "Minus" button if you are using the Wii controller) and select Samus and then your match stage. Release the button, and when the battle begins Samus will shed her armor. Similarly, to play as Sheik, do the same when selecting Zelda, only holding down "A" instead of "R" or the "Minus" button.