Collect all 45 fortune dolls and get boss fighting mode in Options.
Unlimited items or gold:
Find a location that contains multiple items or gold, such as the first room in Oedo Castle. Collect the items, leave the room, then re-enter. The items will be available for recollection.
To avoid getting shot, just switch between characters right before the object hits you.
When you go into a room that has gold or pots of gold like Oedo Castle. Collect the gold, leave the room and then return to that same room. The gold will have magically respawned. you can repeat this as much as needed.
Thanks to Revolution readers Daniel Adler, Skyler Walker, Shawn Toczyl and Iczer!