You need to reflash your GameShark, but to do this you will need another working gameshark, hopefully you have a friend with one, or access to a friendly used game store. Once you get the working gameshark, follow their instructions here:
http://www.madcatz.com/faq/?Action=Q&ID=83
There were two: The battle of Coral Sea stopped the IJN's advance towards Australia, and the battle of Midway stopped their advance everywhere else; because their offensive power was destroyed at Midway (offensive power=aircraft carrier pilots and deck crewmen/the planes & carriers could be replaced, but not the airmen).
Vienna
You need to reflash your gameshark, but to do this you will need another working gameshark, hopefully you have a friend with one, or access to a friendly used game store. Once you get the working gameshark, follow their instructions here: http://www.madcatz.com/faq/?Action=Q&ID=83
Bernard Montgomery
Yes :)
russia
He was stopped at Vienna.
the Pusan Perimeter
It stopped the Japanese advance, and crippled the Japanese Navy.
The meaning of advance is to move forward. An example sentence using the word advance is, If you beat this level of the game, you will advance to the next one.
At the battle of Troyes in 451 A.D., Rome and its allies stopped the Hun advance. Attila withdrew his forces. When he died soon after, the Hun empire collapsed.
The "M" code is the code that must be put on in order to get the other codes to work Gameshark stopped putting up codes for older games you can go to archive.org and type in gameshark.com or you can find it on supercheats.com