At the 'Pause' menu use the D-Pad to enter these codes to enable the effect. To disable model change codes reenter the code in again. You'll know if you've entered the code correctly because you will hear glass smashing as confirmation if it's a model change code and a cat noise if it is a traffic code. If there is no confirmation sound when you enter a code press 'Start' twice to exit and then reenter the 'Pause' menu.

Unlock Model Change - Vending Machine 1:
Press X, Y, X, Y, Up, Down, Left, Right.

Unlock Model Change - Vending Machine 2:
Press X, Y, X, Y, Up, Left, Down, Right.

Unlock Model Change - Ice Machine:
Press X, Y, X, Y, Left, Up, Right, Down.

Unlock Model Change - Modern Phone Booth:
Press X, Y, X, Y, Up, Right, Down, Left.

Unlock Model Change - Potted Plant:
Press X, Y, X, Y, Up, Down, Right, Left.

Unlock Fast Traffic:
Press Right, Up, Y, Y, Up, Right, Down, Up, X.

Complete the following tasks to unlock the corresponding GamerScore.

Versatile Fighter - GamerScore 30:
Perform 99 fighting combos

Warworld - GamerScore 50:
Visited and dominated Warworld

Me aM savE yOU - GamerScore 100:
By you is Bizarro not undefeated!

Metallo Mastered - GamerScore 100:
Defeated Metallo

The Mongul Hordes - GamerScore 100:
Defeated Mongul again

Twisted - GamerScore 100:
Saved Metropolis from the rampaging Tornado


Unlockables
Enter the following codes to unlock the corresponding effect.

Unlock ALL Unlockables (not including Collectibles):
Left, Up, Right, Down, Yellow, Blue, Yellow, Up, Right, Blue.

Unending Stamina:
Up, Up, Down, Down, Left, Right, Left, Right, Yellow, Blue.

Unlock ALL Power-Ups:
Left, Yellow, Right, Blue, Down, Yellow, Up, Down, Blue, Yellow, Blue.

Metropolis Is Indestructable:
Yellow, Right, Yellow, Right, Up, Left, Right, Yellow.

At the menu that allows you to choose Metropolis or Fortress of Solitude when you are loading a game press Up, Right, Down, Right, Up, Left, Down, Right, Up.

Complete the following tasks to unlock the corresponding trophy.

Unlock Globe Bowling Trophy:
Pick up the Daily Planet globe

Unlock Outstanding Valet Trophy:
Pick up 500 Cars

Unlock Bizzaro Unchampion Trophy:
Complete ALL Bizzaro mini-games

Unlock Kitten Finder Extraordinaire:
Rescue ALL 100 Kittens

Unlock Meteor Mayhem:
Complete the 1st level of the game

Unlock Photo Finish:
Defeat 500 enemies

Complete the following tasks to unlock the corresponding costume.

Unlock Golden Age Superman Costume:
Save Metropolis from the tornadoes

Unlock Pod Costume:
Defeat Bizarro

Do the following tasks to unlock the following achievements and their alloted GamerScore.

You Am Bizarro! - GamerScore 20:
Complete The Bizarro Mini-Game.

Armageddon Averted - GamerScore 30:
Complete Level 01: Meteor Storm.

Frequent Flyer - GamerScore 30:
Travel for 10,000 Miles.

Heavy Lifting - GamerScore 30:
During the game lift 10,000 Tons.

Roadside Assistance - GamerScore 30:
During the game pick Up 100 Cars.

Souped-Up Superman - GamerScore 30:
Obtain ALL 15 Power-Ups

Super Sonic - GamerScore 20:
Complete ALL the Fast Flyer Mini-Games

The Greatest Day - GamerScore 30:
Play A Total Of 12 Hours

Mr. What's-his-name - GamerScore 50:
Complete ALL the Mini-Games

Mr. Whiskers - GamerScore 50:
Find ALL the Kittens

Hero of Metropolis - GamerScore 200:
Complete ALL the Metro Events and Mini-Games