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.
Great Tiger - Rushing Magic Attack/Tiger Punch
Don Flamenco - Rose Flurry
Aran Ryan - Double Jab Combo/Headbutt/Rope Attack
Soda Popinski - Rage Uppercuts
Bald Bull - Bull Charge
Super Macho Man - Triple Clothesline
Mr. Sandman - Dreamland Express/Berserker Rage
Donkey Kong - Leaping Attack
Gabby Jay - Taunt Punch
Piston Hurricane - Hurricane Rush
Bob Charlie - Spinning Uppercut
Dragon Chan - Flying Kick
Masked Muscle - Spit
Heike Kagero - Mirage Dance
Mad Clown - Juggle
Narcis Prince - Triple Jab
Hoy Quarlow - Quick Downward Swings
Rick Bruiser - Jump and Uppercut
Nick Bruiser - Jumping Haymaker