i remember a day or so after getting this when it came out i figured out u can warp to an area on another save file. for example, from the prinny grave to the door right outside of it on the other file. Go to the prinny grave (or any other location of your choice) and open the inventory. then press start and Exit. then select a second game file. when u continue on the second file, ull be in the location that file's character was last, but with his inventory up. close the inventory and go into any door, and ull be at the door right outside of the prinny graveyard, letting the second file get the prinny cap (this even works on a brand new file). using the same method u can get the new file back to the beginner area no problem, since theres a save file in the prinny graveyard so u can keep the prinny cap. this can work for several other locations as well. it may be possible to get the nemesis early game using this method as well, havent tested it to make sure though. but you cannot use it to get to points in the game that happen at a specific time. for example u cant get the lazer until you would have been able to get it normally. and if you try to go to the hell place, itll just be empty. no time limit, no enemies, etc.
not sure if anyone posted this before, so im doing it just incase. very fun to mess with