When awarded a new character or outfit after completing the Professional Championship or better, go into any fighting mode (for example, Single Fight, Survival, etc.). Highlight that character, then press Select. Note: New characters are the person you just defeated that championship with, but will have a different hair, costume, glove color, and record. For example, Mickey McFists record is 12 wins 3 loss and 9 KOs, but "Joe Nitro" has 15 wins 2 loss and 11 KOs.

Character	How to unlock
Evil Jackpot	Win the World Title with Jackpot (wearing the player two costume).
Ice Berg	Win World Title with Tiny. He has a solid record of 99 wins/KOs and 0 loss.
Jackpot (player two costume)	Win Professional Championship with him.
Joe Nitro	Win the Professional Championship with Mickey McFist.
Joe Nitro (alternate costume)	Win World Title with Joe Nitro..
Major Flag new costume	Win the Professional Championship with him, then highlight him and press Select. His shirt will be purple.
Miagaru new costume (yellow)	Win the World Title with him.
Miagaru player two costume (white)	Win the Professional Championship with him.
Psycho Tick	Win the Professional Championship using The Hammer.
Royal Pain new costume	Win the World Title with him. When done, highlight him and press Select. His skin will be orange.
Royal Pain player two costume	Win the Professional Championship with him, then highlight him and press Select. He will have pale skin.
Sgt. Drill	Win the Professional Championship using Major Flag.
Tiny new costume	Win the Professional Championship,with him, then highlight him and press Select. His skin will be gray.
Violent Violet	Win the Professional Championship with Knuckles Nadine.
Wendy Wacker	Win the World Title using Violent Violet.