Start a 1 player or Vs Mode game. Choose Jigglypuff or Luigi to be your character, and a stage. While you play in a game, try one of your characters' techniques. If you chose Luigi, run next to an enemy character and hold up on the control stick. Then press B, if you hear a "Cling" noise, you done the attack correctly. If you have chosen Jigglypuff, approach an enemy character and get very close, then hold down on the control stick, then press B.

Note: Each of these attacks can make an easy knock-off.