Characters
Once you meet the unlock conditions for a character, they'll challenge you to a battle the next time you complete Classic mode, or a round in Smash. You must defeat them in a one-stock battle before they'll be playable. If you lose, don't worry too much. You won't have to meet the requirements again. They'll show up again next time you play a round of Smash. There are two ways to unlock each character. One is to play a certain number of Smash matches. (One character becomes available every 10 matches.) The other differs by character. Below is a list of unlockable characters, along with the number of Smash matches required to unlock them, and their alternate unlock requirements.
10 – Ness – Complete Classic mode on any difficulty
20 – Falco – Complete Classic mode on any difficulty without using continues
30 – Wario – Complete 100-man Smash
40 – Lucina – Complete Classic mode with Marth without using continues
50 – Dark Pit – Complete Classic mode with 3 characters
60 – Dr. Mario – Complete Classic mode with Mario on Intensity 4.0 or higher
70 – R.O.B. – Collect 200 unique trophies (very easy to do with Trophy Rush)
80 – Ganondorf – Complete Classic mode as Link or Zelda on Intensity 5.0 or higher
90 – Mr. Game & Watch – Complete Classic with 10 characters
100 – Bowser Jr. – Complete Classic mode as Bowser on Intensity 6.0 or higher
110 – Duck Hunt – Complete Classic mode with 15 characters
120 – Jigglypuff – Collect 30 different equipment items
Stages
Stages are unlocked by clearing challenges.
Magicant – Unlock Ness
WarioWare Inc. – Unlock Wario
Pac-Maze – Use Pac-Man's final smash
Balloon Fight – Use Villager in Smash 3 times
Dream Land – Use Kirby's final smash
Mute City – Win 3 Smash battles as Captain Falcon
Flat Zone 2 – Unlock Mr. Game & Watch