This cheat will get you to lv 20 in the 1st battle you are in! Here's the code:

12173168 0000D160

This cheat is reeeeally easy 2 put in & was tested

Ok these three codes can help you beat the game.

Invincible
92172a94 fff70000
D9000000 02172a94
D4000000 00000008
D6000000 02172a94
D2000000 00000000

Infinite Energy
92172a94 feff0000
D9000000 02172a94
D4000000 00000100
D6000000 02172a94
D2000000 00000000

G1 Starscream(Decepticons)/Skydive(Autobots)
620adc2c 00000000
B20adc2c 00000000
00000004 00000001
D2000000 00000000

Ok now kill some Autobots/Decepticons!

Game ID:AFZE D381C56E

Infinite life/weapon energy :
520DAC50 E8BD8070
020DAC54 E5902134
020DAC60 E580213C
020DAC6C E5902138
020DAC78 E5802140
020DAC80 E5802040
D2000000 00000000

Tap R to be at max xp-1 (ie. One xp needed to level up)
520DAC50 E8BD8070
020C9158 E5906008
020C9174 E5905004
02024D54 E7920100
020C9168 E1A04000
94000130 FEFF0000
020C9158 E5905004
020C9174 E5806008
02024D54 E7924100
020C9168 E2446001
D2000000 00000000

Get a Specific Vehicle from a scan
020331B4 03A040XX
The digits:
Beater - 00
Sportster - 01
SUV - 02
Armored Truck - 03
Chopper - 04
Notchback - 05
Import - 06
Attack Copter - 07
Peace Van - 08
Pickup - 09
Utility - 0A
Pickup Car - 0B
Moving Truck - 0C
School Bus - 0D
Longhorn - 0E
Gunner - 0F
Flame Truck - 10
Ice Cream Truck - 11
Recon Chopper - 12
Lightning Rider - 13
Death Truck - 14
Tricked Out Car - 15
Funky Bus - 16
Racer - 17
Maintenance Truck - 18
Hot Rodder - 19
Stealth Chopper - 1A
Safari Truck - 1B
SWAT Van - 1C
News Copter - 1D
Off-Roader - 1E
Raider - 1F
Speedster - 20
Police Copter - 21
Transport - 22
Prison Bus - 23

Unlock Skydive form(only needs to be used once):
620ADC2C 00000000
B20ADC2C 00000000
00000004 00000001
D2000000 00000000

Have all cheats(as long as the code is activated)
520E4B14 E3A0000C
020E4B18 E1A0900B
020E5004 E1A00000
D2000000 00000000

Select between Autobots (L) and Decepticons (R) Vehicles *
620ADB94 00000000
B20ADB94 00000000
B000000C 00000000
94000130 FDFF0000
00000008 0000000A
0000001C 00000000
D1000000 00000000
94000130 FEFF0000
00000008 00000054
0000001C 00000001
D2000000 00000000
Press R or L before accessing the vehicle list to choose between the Autobots and Decepticons vehicles list.
If you select a vehicle from the list of the other game, you'll HAVE TO have the codes activated and press L or R each time before accessing the vehicle list again, else the game will crash.
As the games save the vehicle you choose, if you select a vehicle from the list of the other game and reboot your game then access the vehicle list without using the codes, the game will always crash. To fix that, use the codes and press L or R.
You'll also notice than when you select a vehicle that is not 'made' for your game, some colors in the game will be 'wrong' (will be red instead of grey, and vice-versa).
The Arctic will be changed to Quatar Desert. All missions will be the Decepticon ones if you press R.
Moreover, using the codes will change the names of the missions (but they will still be the same), and might have other side effects...
WARNING! If you use these codes, you CANNOT access wifi. All of these codes work because I have tested them.
So be very cautious when using these codes !... (and don't hesitate to report any unknown side effect).