Unlock All in Shop Zone:
At the Start Menu, hold L + R and press White, Black, then A + B + X + Y, then Start. The effect only lasts for one match, but may be repeated whenever you like.

Import an Offline Wrestler to Xbox Live:
Go into CAS mode while you are logged onto Xbox Live. Then duplicate your wrestler and that clone will work online. To edit him, you will have to be signed onto Xbox Live.

Infinite Cash:
Copy your active profile to a memory card, then buy any item. Afterwards, go to that data you just copied to the memory card and copy it back onto your Xbox. You will have the item and your money will be restored.

Thanks to Revolution reader Deadstar!