63 Extra Lives
When you are at the title screen, press and hold:
B, A, Down, Up, Down, Up simultaneously on the 2nd controller. Press Start on Controller #1 (while still holding all those buttons) to gain 63 extra lives.
Fast Power-up for the Flame Punch
Press and hold A to begin powering up the Flame Punch. Immediately press Start to pause the game while still holding A. The punch will continue to power up while the game is paused. When ready unpause the game (while still holding A) and you will have a fully powered Flame Punch ready in minimal game-time.