Pro Action Replay Codes:
Invincible - 00C19E:01 -Rid
Mega Power [Note 1] - 00C1B1:02 -Rid
Note 1: Turn Action Replay on after game starts.
Infinite Lives - 00C197:09 -Rune
Infinite Health - 00C196:05 -Rune
Infinite Continues [Note 2] - 00C195:09 -Rune
Note 2: The game might get glitchy after you continue. The glitches don't seem to have any long-term effects on gameplay.
Invulnerability - 00C19E:FF

Game Genie codes:
Invulnerability - 001-2DC-3B4