Easy Money:
If you're low on money, go to any arena. Save, then temporarily recruit one of the gladiators (the one that looks like he has the most expensive equipment). Then go out to the map and walk around on the grassy areas (or the sandy for the southern expans) untill you get into a fight. Then put in the temporary recruit and whoever else you want to put in. Put the recruit as close to the enemy as possible. Then put whoever else as far away as possible. Let the temporary recruit get killed then go with someone else and get the chest he left. Then you can chose to leave or kill the rest. Then go to any shop and sell whatever you got. Enjoy.

Remove equipment limitations:
Pause the game at your school and press Right, Down, Left, Up, Left, Left, Left, Left, , , .

Extra Money:
Pause the game at your school and press Right, Down, Left, Up, Left, Left, Left, Left, , Left.

Extra Experience:
Pause the game at your school and press Right, Down, Left, Up, Left, Left, Left, Left, , Right.

Control camera view:
Pause the game during combat and press Up, Left, Down, Right, Left, Left, Left, Left, Up, Up, Up, Up.

Higher level enemies:
Pause the game at a League Office and press Right, Right, Right, Up, Up, Left, Left, Left, Left, Right, Up, Up, Up, Up, Down. Repeat to increase levels.

Lower level enemies:
Pause the game at a League Office and press Right, Right, Right, Up, Up, Left, Left, Left, Left, Right, Down, Down, Down, Down, Up. Repeat to decrease levels.

Increase HP:
Pause the game at a League Office and press Down, Right, Up, Left, Left, Left, Left, Left, , Up.

Increase defensive affinitTriangle:
Pause the game at a League Office and press Down, Right, Up, Left, Left, Left, Left, Left, , Left.

Increase offensive affinitTriangle:
Pause the game at a League Office and press Down, Right, Up, Left, Left, Left, Left, Left,, Right.

Normal timer speed in timed battles:
Pause the game at a League Office and press Right, Up, Left, Down, Left, Left, Left, Left, Up, Down.

Faster timer speed in timed battles:
Pause the game at a League Office and press Right, Up, Left, Down, Left, Left, Left, Left, Down, Up.

Berserk team:
Pause the game at a League Office and press Left, Down, Right, Up,Left, Left, Left, Left, Up, Right, Down, Left.

No random encounters:
Pause the game at the World Map and press Right, Left, Up, Down, Left, Left, Left, Left, , , .

Restore random encounters:
Pause the game at the World Map and press Right, Left, Up, Down, Left, Left, Left, Left, , , .

Secret Battle:
If you walk around Nordaugh, you will eventually see the guy that killed Ludo's dad. Talk to him, and he will tell you to leave him alone. Keep talking to him, and he will eventually fight you.

Thanks to Revolution readers FloydFan, Narcolepticon, JuicyJuice,TK RICO and Big 69!