Video Games Dynasty Warriors 4 Cheats?

I rented DW4 not too long ago form GameFly. I won't have the game long enough to unlock all the characters manually. I looked on the internet for cheats and got ones that were like L1, L1, R1, R1, square, square, triangle, triangle. I tried it along with the others on the site, but none of them worked. I figured they were fake but upon searching for more codes, every site would give me the exact cheats.
So my questions are: Are there any cheats to DW4? What are they? Or are the ones I'm finding real and I'm just doing something wrong?

By the way DW4 is an awsome game and I recommend anyone who has not played it to give it a try.

 

Why bother cheating? Cheating in a game that great is weak. And you can't be a Hero of Musou if you are weak. Why not just play the game as it was meant to be played?
Don't be such a Zhang He. Be more of a Lu Bu next time.

 

Let me remind that I will have this game for one more just a few days.... it's not possable to unlock so many secrets with the time I have... I have other things to do. My mom wants the Diao twins which is the main reason for my seeking any cheats. And I'd like to play with the opening movie editor just once before I send it back. >_>

I own DW3 and unlocked everything in it the long way.

Don't like Lu Bu... Zhou Yun is the ultimate hero.

 

Cheats:
www.gamefaqs.com

For all your cheating needs

- Teddz

 

Seriously, though, between myself and my roommate we beat all the campaigns in two days. It's not that hard.