Transformers: Dark of the Moon Cheats - Xbox 360

Unlock Ratchet and Shockwave
Go to the "Unlockables" screen and press [Up], [Right], [Down], [Left], [Up], [Start].

Achievements
Complete each achievement to receive the allotted gamerscore:

Prime (125) - Complete the Campaign.
Completionist (25) - Destroy all hidden TRANSFORMERS symbols in Campaign.
Chapter II (25) - Complete Chapter II on any difficulty.
Top Score: Ironhide (25) - Complete Chapter II with a score of 1,000,000 or more.
Seek and Destroy (25) - Kill 25 Enemies using Grenade Blossom in Chapter II.
Rule With An Iron Fist (25) - Kill 20 enemies with Ironhide's Melee attack in Chapter II.
Chapter III (25) - Complete Chapter III on any difficulty.
Top Score: Mirage (25) - Complete Chapter III with a score of 800,000 or more.
Body Count (25) - While holding out for Reynolds to send backup in Chapter III, 30 Decepticons are killed.
Road Kill (25) - Destroy 30 enemies while in vehicle form in Campaign.
Grenade Expert (25) - Eliminate 20 opponents with the Flak Grenade in Campaign.
Recruit (25) - Survive 60 seconds in a public multiplayer match without being killed.
Power Surge (25) - Use an active ability 5 times in a public multiplayer match.
The Champion (25) - Reach level 20 in any single class in Multiplayer.
Chapter I (25) - Complete Chapter I on any difficulty.
Top Score: Bumblebee (25) - Complete Chapter I with a score of 1,000,000 or more.
I know what I'm doing! (25) - Change into vehicle form before reaching the change form tutorial in Chapter I.
Boot Stomper (25) - Kill 3 Enemies with Bumblebee's Kick Ability in Chapter I.
Homewrecker (25) - Wipe out all secret base ground defenders within 60 seconds in Chapter V.
Furious Flyer (25) - Fly through the canyons after Air Raid in 120 seconds in Chapter V.
Surprise Package (25) - In the air battle, activate Starscream's Guided Missile ability 5 times without dying in Chapter V.
Chapter VI (25) - Complete Chapter VI on any difficulty.
Good Driver Discount (25) - Avoid taking any damage from Starscream's proximity mines in Chapter III.
Chapter IV (25) - Complete Chapter IV on any difficulty.
Top Score: Soundwave (25) - Complete Chapter IV with a score of 1,000,000 or more.
Serrated (25) - Kill 10 Autobots with Laserbeak's ram ability in Chapter IV.
Stunning! (25) - Stun 10 Autobots with Soundwave's stun ability in Chapter IV.
Chapter V (25) - Complete Chapter V on any difficulty.
Top Score: Megatron (25) - Complete Chapter VI with a score of 2,000,000 or more.
Autobots are Weak! (25) - Defeat all 3 waves in Megatron's Lair without dying on Hard Difficulty in Chapter VI.
Overlord (25) - Drain 5,000 health from enemies in Chapter VI.
Chapter VII (25) - Complete Chapter VII on any difficulty.
Fleet of Foot (25) - When one Driller arm is attacking, avoid all attacks in Chapter VII.
Counting Coup (25) - Use only melee attacks on Shockwave's power core to make him retreat to his cryo platform.
Primed for Combat (25) - Activate Optimus' Shoulder Rocket ability 5 times without dying in Chapter VII.

Additionally, there is one secret achievement:

Sacrifice (25) - Be the first one eliminated in a public multiplayer match.

Unlock Multiplayer Characters
Ratchet - Complete the campaign.
Shockwave - Complete the campaign.