Game 1: Avatar: The Last Airbender

Guides

Console games
PS2: FAQ/Walkthrough - Complete guide plus list of items and enemies, and info on the Four Nations game and sidequests. (by AtelierMana, hosted at GameFAQs)
Wii: FAQ/Walkthrough - Complete guide plus enemy info and item locations. (by Nexus_of_Sanity, hosted at GameFAQs)

Nintendo DS
FAQ/Walkthrough - Complete guide plus info on events, enemies, and mini-games. (by RocketJess, hosted at GameFAQs)
Herb Mix List - Herb locations and lists the combination creations. (by iyqyqr, hosted at GameFAQs)
Omashu Library Map - Image and guide to get past the guards. (by RocketJess, hosted at GameFAQs)

Gameboy Advance
FAQ/Walkthrough - Complete guide including item locations and attack info. (by Shotgunnova, hosted at GameFAQs)
Boss FAQ - Details on how to defeat all of the bosses and minor enemies. (by Shotgunnova, hosted at GameFAQs)

PC
n/a. Unfortunate, since the storyline is different from the other console games.

PlayStation Portable
n/a. The storyline is the same as the console games though, so those guides will be useful.


Cheat Codes

Go to the Code Entry section in the Extras Menu to enter the codes. Only works for the Wii, XBox, PS2, and PSP versions of the game. (Thank you GameFAQs for all the codes)


24463 - Infinite Chi
94677 - Infinite Health
53467 - Infinite Stealth
23637 - Infinite Copper
34743 - Double Damage
54641 - One Hit Dishonor
37437 - All Treasure Maps Unlocked
97831 - Unlocks Character Concept Gallery