Cheat codes:

Level select:
     Enter 8ODYS as a code.

Invincibility:
     Enter HPPYHPPY as a code.

All weapons:
     Enter RCKTSRDGLTR as a code.

Campaign mode bonus level:
     Enter  WRDRB  as  a  code to unlock a secret level after campaign
mode is completed.

Invincibility:
     Enter MSTSRVV as a code.

Custom 1 gang:
     Enter TRDDYBRRKS as a code to unlock the Custom 1 gang (M2 Hydra
tank) in multi-player mode.

Brandon Game:
     Enter NNKNHCKS as a code

Weapon Power-up:
     Get  15 of some items and press the a,b and z buttons to make the
weapon stronger.

Suicide:
     Press  C-Up + C-Down + C-Left + C-Right during game play. This is
especially  useful  if  you  have  selected  the  wrong  tank with the
invincibility code activated.

5 ways to destroy the Rhino:

     1.  If  you use the flamethrower, you don't have to get along the
sides  of  the  Rhino  to  kill  it. It's front armor is invincible to
anything except the flamethrower.

     2.  Lay a lot of gun buddies down so when the Rhino tries to kill
you or the gun buddies, one of you will get a clear shot.

     3.  Use the cloaking to make yourself invisible and you should be
able to get around him without him knowing where you are.

     4.  Fire  a  guided  missile  and guide it around the Rhino for a
clear shot

     5.  Be  the FLP-E & then use your side step to quickly run around
his defense.

Mines, Swarmers, and Lasers:

     With MINES as your chosen weapon: Press A+B simultaneously and it
will lay down all of your mines behind you.

     With  SWARMERS as your chosen weapon: Press A+B simultaneouly and
it will fire all your swarmers in rapidsuccession.

     With  LASERS as your weapon: Press A+B simultaneously and it will
shoot  your laser causing a multi ricochet. Note: It will not ricochet
off tanks.

     This cheat appears to work on every level and against every tank.
I think you need the ALL WEAPONS code for this to work correctly. (All
weapons code: PLVRZM)

Passwords:

     To  play  on  a  particular  level, highlight "Input Code" at the
Options screen and enter its corresponding password.

Level 01: Ground Zero - FRHBMCTNTK
Level 02: The Tunnel - LHTSPMFRGS
Level 03: Times Square - NGLFFPTTFP
Level 04: Stranglehold Bridge - SHPPNRVWGB
Level 05: Bonus Level - MRFFCRTKP
Level 06: Heartland - LPGCVBBJCF
Level 07: Lake Shore Drive - GLWHJCRNLK
Level 08: State Street - KMKJTMHRNS
Level 09: Bonus Level - FLWWFCWNRK
Level 10: Armageddon Highway - WSMBCPVRWS
Level 11: Area 51 - CGJWVRGLNM
Level 12: Fremont Street - KVVLHFHWTB
Level 13: Bonus Level - FCLPJRWTMP
Level 14: Crimson Gate - TMFNJMKJGF
Level 15: Warf - PPJLJHRCVV
Level 16: Bonus Level - LNKNSWKGTH
Level 17: Q-Zone - WMNRSMRTR 

Avoid Nukes (multi-player only):
     First  of  all start with shadow ops as a team or get teleporters
from  the weaponds on the ground. When you hear "nuke deployed" switch
to  the  teleporters  and  when  the  screen turns yellow fire the the
teleporters  once  only.  this  code needs some timing amd if your are
right by the nuke when it explodes the cheat will not work.

Nuggets of Wisdom:
     To  get  some  nuggets of wisdom from the Battle Tanx team, first
make your way to the Arizona truck stop. It's about the third stage in
one  player  mode. Get some guided missiles and go back to about where
you  started  the  stage. Control a guided missile to the dessert that
should  be to your left. You should see a white car, hit it. There you
go! Little mesages should scroll at the bottom of the screen.