Alright grab the disc. Now hold A for 2 maybe 3 seconds. Now roll your finger to the B and hold it like you would power up a deathrow. You should hear the sound but the disc will still be blue. This means you can hold it for as long as you want without it blowing up on you.
More Credits - Hold the WHITE button down for 1 minute on the "Manage Team" screen. The number of extra credits you recieve depends on the difficulty. To do this more than once, you will have to reboot the Xbox.
Unlock All Arenas Name player #4's controller as "MOREROOM".
Unlock All Teams and Players - Name Player #4's controller ID as "ALL150".
Unlock Everything - Enter your profile name as "SouthEnd" and capitalize the "S" and "E".
Unlock Extreme Difficulty Name Player #4's controller as "NO FEAR".
Unlock Multidisc Name Player #4's controller as "CONFUSED"