Instructions
 
Fight as normal, getting your opponent into his second health bar, which is red. 
Continue doing damage to your opponent until his health bar is near the flashing red zone, or the last quarter of the bar. 
Start a combo, and at any point during the combo, input your character's Ultra ending. The Ultra ending is a character-specific button sequence that you use to trigger the Ultra move; it can only work if you execute the ending input when your opponent's health bar is flashing red. Each character's Ultra ending input is as follows: 
B. Orchid: hold Away, press Forward + Medium Punch 
Chief Thunder: hold Away, press Forward + Quick Punch 
Cinder: press Forward, Forward + Fierce Punch 
Fulgore: press Forward, Down, Down-Forward + Quick Punch 
Glacius: hold Away, press Forward + Fierce Punch 
Jago: roll the Control Pad from Down-Forward to Down-Away + Quick Kick 
Riptor: hold Away, press Forward + Quick Kick 
Sabrewulf: hold Forward, press Away + Quick Kick 
Spinal: roll from Down to Forward + Fierce Punch 
T.J. Combo: hold Forward, press Away + Fierce Punch