A Signature Move is the most powerful move in a character's arsenal. A list is as follows;
NOTE: The slashes between some attacks indicate their Title Defense attack in Punch-Out!! for the Wii, along with their Contender attack. For Aran Ryan's moves, the attack to the left of the semicolon indicates his attack in Super Punch-Out!! for the SNES; the attacks to the right indicate the ones in Punch-Out!! for the Wii. For Mr. Sandman's, the attack on the left indicates his attack for all games besides Super Punch-Out!!, and the attack on the right indicates the one in Super Punch-Out!!.
Doc Louis - Star Punch
Glass Joe - Vive La France Taunt/Liberte Taunt
Von Kaiser - Von Kaiser Wave
Disco Kid - Disco Flurry
King Hippo - Hippo Squeeze/Hippo Squeeze 'n Squash
Piston Hondo - Hondo Rush
Bear Hugger - Bear Hug/Catch and Release
Great Tiger - Rushing Magic Attack/Mirage Dance
Don Flamenco - Rose Flurry
Aran Ryan - Shamrock Squeeze; Headbutt/Irish Whip
Soda Popinski - Soda Fury
Bald Bull - Bull Charge
Super Macho Man - Super Macho Clothesline Attack
Mr. Sandman - Dreamland Express; Midnight Sleeper
Donkey Kong - Leaping Attack
Gabby Jay - Yay Taunt
Piston Hurricane - Hurricane Rush
Bob Charlie - Shuck and Jive
Dragon Chan - Dragon Kick
Masked Muscle - Spit
Heike Kagero - Mirage Dance
Mad Clown - Show Time
Narcis Prince - London Lashings
Hoy Quarlow - Staff Wave
Rick Bruiser - The Rumbler Blow
Nick Bruiser - Dashing Forearm