Digimon World 4

If you chose Agumon in the beginning, go on the Ghost Extermination sidequest in the Shrine of Seals and clear the dungeon with more than ten minutes remaining. Do this in Hard Mode. If you chose Veemon in the beginning, clear Item Road after you complete the game. If you chose Guilmon in the beginning, clear the Undead Yard in Hard Mode, killing all 302 enemies and have ten minutes or more remaining. You also need to activate all the "Concealment Gates". -If you chose Dorumon in the beginning, clear Undead Yard, defeating all 279 enemies within thirty minutes.

To unlock Imperaildramon PM., you must beat Wamu Platform (Wormhole) Dungeon in Super Hard Mode.

If you chose Agumon or Guilmon in the beginning, go on the "Treasure Hunt" sidequest set by the Digi-Elfs in the Central Area. Complete the dungeon, and bring back the Sword Cannon Delta. This must be done on Hard mode. If you chose Veemon in the beginning, complete Item Road after you complete Hard mode. If you chose Dorumon in the beginning, you can get him by going on the Booster Pack Collection sidequest set by the Digi-Elfs in the Terminal Area and completing the dungeon with only 1 HP, without recovering your HP or using a Gate Disk. This must be done on Hard mode.

The following can be done while playing in either single player or multi-player mode. However, for the mode to become unlocked in multi-player, you must switch your players to the first slot.

Fourth MP Move: Increase your Blast Technique to about 1,000.
Hard mode: Successfully complete Normal mode; this applies to player one only. To unlock it for other players, switch them to the first slot.
Increase MP Power Moves: Keep repeating your MP Moves. Notice that the Tech Ups will increase about 300 tech points and you will level up your move from Petty to Magna.
Super Hard mode: Successfully complete Hard mode; this applies to player one only. To unlock it for other players, switch them to the first slot.

If playing as Agumon, train your Blunt skill to the amount needed for a Bash skill weapon. When you have enough, you are able to equip the Bash weapon when your Bash skill is only 1. Note: When you tech-up on that Bash weapon it will not increase your Bash skill, but will increase your Blunt skill instead.

Note: This must be done with in a game with multiple players. If one or more of your allies are dead, go into a cave or another place where the game will load. Your allies should be back with full health and you do not need to use a disc to revive them. Note: If you or your allies die, then the amount of the dead Digimons' experience it needs to level up still doubles, and you will also lose all the money that carried with you on that mission.

The following weapons in Hard mode will be different from what the dialog states when you check it in the inventory.

The dialog says Death Crimson, but it is a Dark Crimson.
The dialog says Death Bringer, but it is a Doom Bringer.
The dialog says Death Raptor, but it is an Omega Raptor.

Get five Digivolve Techs on Hard mode to unlock the Undead Yard quest.

This trick requires your main Digimon as player one and any Digimon as player two. Give all your Bits to player two. Then, save player two at the Save Keeper. Next, have player two give all Bits to player one. After that, have player two quit the game at the Save Keeper, but this time without saving. Then, go to Call Keeper and have player two join in again with the same Digimon. Repeat this from the beginning until you have 9,999,999 bits, both in the bank and pocket. You can also use this trick to duplicate items. This is very useful if you want to give some rare weapons and armor to a friend.

To unlock the following digivolutions, you need to reach level 16 and speak to the DigiLab attendant to unlock the Digivolve technique