Special Codes/cheats for Metal Slug 1/2 for Neo Geo Pocket?

I wanted to ask if there are any special Codes, cheats that allow one to completere Metal Slug 1/2 for Neo Geo Pocket?

I ask because I wanted to unlock all levels to experience the entire game. Do not flame me, as I will go back and play all with out cheat codes. I noticed www.gamefaqs.com did not have any cheats for the Neo Geo Pocket. Also, how would one enter these cheat codes?

Regards Tracy

i dont think there are any codes, but there's hidden stuff, and stuff you get for beating the games etc.

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