When you are Ironhide and fighting the Cement Truck Decepticon you can defeat him by transforming and running him over to knock him down and then picking him up and throwing him.

At the menu that has 'Bonus Features' and 'Campaign' listed enter the following codes to unlock the corresponding effect.

Unlock ALL Missions:
Press Down, Up, Left, Right, Right, Right, Up, Down.

Unlock Infinite Ammo:
Press Up, Down, Left, Right, Up, Up, Down.

Unlock Infinite Health:
Press Up, Down, Left, Right, Down, Down, Up.

Unlock G1 Megatron:
Press Down, Left, Left, Down, Right, Right, Up.

Unlock Robovision Optimus Prime Skin:
Press Down, Down, Up, Up, Right, Right, Right.

No Cops Attack and No Vehicle's Running on the Street:
Press Right, Left, Right, Left, Right, Left, Right.

Unlock Cybertron Decepticon Missions and Bonus Cybertron Autobot:
Press Right, Up, Up, Down, Right, Left, Left.

Using the D-Pad enter the following codes during Optimus Prime, Starscream or Jazz's missions to unlock the G1 skins.

Unlock Starscream G1 Skin:
Press Right, Down, Left, Left, Down, Up, Up.

Unlock Optimus Prime G1 Skin:
Press Down, Down, Up, Up, Right, Right, Right.

Unlock Jazz G1 Skin:
Press Left, Up, Down, Down, Left, Up, Right.