Ring King

Invincibility:
Enter the "Training Gym" screen. Press A on controller two, A, Select, A on controller one, B on controller two, Select on controller one, A, B on controller two, and B(2) on controller one.

Final match:
Enter 92E8X2B6H2906A7XKC44S9 as a password.

Super passwords:
Enter SLAYER 1 as a name (by changing the P to an S) and enter ATTC75T4E4F as your password. You will have 99 energy and can enter training, ranking, tournament, player vs. player modes.
Information in this section was contributed by Jacob Kleiman.

Enter 6P0BKPY3LS3 as a password for an undefeated record.
Information in this section was contributed by Gregory Barton.

Change "Player1" to "Slayer1" in training mode or ranking mode and enter 77ZH54GC3M8 as your password for 182 wins, no losses, and 175 KOs.
Information in this section was contributed by J.P. Sandoval.

Change "Player1" to "Slayer1" in training mode or ranking mode and enter BTI75667FGY as your password for 207 wins, no losses, and 200 KOs.
Information in this section was contributed by J.P. Sandoval.

Hint: Faster energy recovery:
Use a controller with an auto-fire feature to reenergize quicker between rounds.
Information in this section was contributed by Jacob Kleiman.