At the main menu, press R1, R2, L1, L2, Square(2), Triangle(2) to unlock all generals.
Have a saved game file from Dynasty Warriors 4 or Dynasty Warriors 4: Xtreme Legends on your memory card to automatically unlocked pictures 1 through 126 in the gallery. Additionally, successfully complete empire mode with certain characters in your employ to unlock the original character artwork in the archives section. Save the game history after the credits, and the art can now be seen.
Finish the 100 turns allowed in any one campaign, but do not actually conquer China. There must be at least one area not under your control at the end of the 100th turn.
To get a level 11 weapon, raise a General to Grand General and put him on the field with a player that has a level 10 weapon. The level 11 weapon will have four random high level items attached to it.
When you have to defend your base, you do not have to win that level by taking the enemy's base. You can just wait until the time runs out to win. Additionally, ally with your biggest enemy, and when he gets attacked join the battle. Do not put anything on; just start the battle, then retreat. He will lose that region. You can also make him lose an attack by doing the same thing.
In historical mode, play as anyone's force except for Dong Zhuo. When the regional lords join up to fight Dong Zhuo, do not participate. The region lords will lose and Dong Zhuo will continue to rule the land. Eventually Lu Bu and Diao Chan will talk about betraying Dong Zhuo. An intermission sequence of Lu Bu fighting some of of Dong Zhuo's men will start. After this, Lu Bu becomes his own force.
While playing the game, hold Start + Select to return to the main menu.