Go to the town area with the Moon Lighter or Moon Lighter item. Save the game at Sword's House, then go to the VMU machine in the Monster House. Download the "Moon Lighter" or "Moon Lighter S" mini-game to the VMU. Download the monster to be duplicated to the VMU. After downloading, exit the Monster House, then turn off the Dreamcast without saving again. Start the game again and select the destination save file. Go to the Monster House and load the monster from the VMU into the game. If done correctly, both save files will now have a copy of the same monster.
Get Cooks
Defeat all of the dungeons. (Be sure you save it after you defeat the last dungeon.) When you defeat the last dungeon, go get Lady, save it, and then go close the book. Wait for all the credits to end, you will see a movie, after the movie it will ask if you want to save it or not, save it, and load your game back up. Go to your monster house, go to encapsulate monster, and there you will find the name "Cooks" Take him out, and he'll be one of your monsters!
Infinite Money
This will help get rid of your money problems. Go to the hardware store and sell everything you have and you can go to Mr. Noimen and sell your frost ring or what you might have that he buys. After you have sold everything go to the place where you buy tokens and buy as many as you can. Then put them into your VMU. Then you reload your game and you will still have all the stuff you just sold cause you didn't save it and you have the tokens in your VMU the worth $50 a piece so then you can keep doing that. With the tokens you can buy really good rings. Don't sell your stuff !
Lady
Finish the dungeon "Downtown".
Lady's Cook
Beat the game once.
Marion
To unlock Marion you need the item Marion Doll, which can randomly appear in the dungeon "Doll's House". Once you get it, go to Noiman's house and Noiman will take the doll. Now, go to any dungeon and when you get out of it (by either escaping, losing or finishing it), go back to Noiman's house. After a cut-scene, you'll be able to play as Marion.
Mini games more than once
Download a mini-game to the VMU. Turn off the Dreamcast without saving the game. If done correctly, the mini-game will be on the VMU and still will be in the game without having to re-purchase it. Note: To save money, do not save the game after buying the mini-game item.
Nigel
Finish the dungeon "Phantom Zone".
Play as Jogurt from Shining Force
To play as the mascot hamster from Shining Force, you need to obtain and equip the "Jogurt Ring", which is often found randomly in dungeons or given as a reward for quests that offer rare items. This Easter Egg is a reference to a special ring you can get if you defeat an enemy in battle with Jogurt, which, once equipped, turned characters into replicas of Jogurt himself.