When electrocuting a character, notice that you can briefly see their skeleton, arrange a 2 player battle with samus and (pikachu or ness.) Notice when you electrocute samus, no skeleton... hmm... try again, except this time, have the person playing samus... more
To get the secret stage you have to win the game with 3 stocks, any continues, any difficulty level and with every player including the secret ones. The secret stage is from the first Mario game.
Jigglypuff=Win the... more
If you beat all the Practice challenges with all 12 characters, (8 normal and 4 secret) you will unlock the Sound Test option.
If you play 50 multiplayer games, you will unlock the Item Switch.
If you beat the game with all 12 characters, you will get... more