Here's a list of my favorite taunts for each character.
Mario: All 3
Donkey Kong: All 3
Link: /\ taunt, \/ taunt
Samus: All 3
Yoshi: /\ taunt, \/ taunt
Kirby: All 3
Fox: <> taunt, \/ taunt
Pikachu: /\ taunt, <> taunt
Luigi: All 3
Captain Falcon: <> taunt, \/ taunt
Ness: All 3
Jigglypuff: All 3
Bowser: /\ taunt, <> taunt
Peach: <> taunt, \/ taunt
Zelda: /\ taunt, <> taunt
Sheik: All 3
Ice Climbers: All 3
Mr. G&W: All 3
Marth: All 3
Falco: All 3
Ganondorf: <> taunt, \/ taunt
Meta Knight: All 3
Pit: All 3
Wario: /\ taunt, \/ taunt
Zero Suit Samus: Don't use her much
Ike: All 3
Squirtle: /\ taunt, <> taunt
Ivysaur: \/ taunt
Charizard: All 3
Diddy Kong: /\ taunt, \/ taunt
Lucas: /\ taunt, <> taunt
King Dedede: <> taunt, \/ taunt
Olimar: /\ taunt
Lucario: /\ taunt, \/ taunt
R.O.B.: /\ taunt, \/ taunt
Toon Link: /\ taunt, <> taunt
Wolf: <> taunt (gotta love his quote), \/ taunt
Solid Snake: Every taunt involves that box
Sonic: All 3