The following are known Action Replay Codes for Mystical Ninja Starring Goemon on Nintendo 64 (N64).

Device Compatibility: Action Replay & GameShark

Infinite Health
8015c5e70028

Infinite Lives
8015c5ef0009

Infinite Ryo (Money)
8115c5ea270f

Press L Button To Levitate
d00c7d3b0020
8116a0444000