Some of these codes are double (tough), they are in TXT format, so everyone can see them. These codes are for Pokemon Red/Blue versions, when I get others-- They will be posted!!!
Click Here For Gameshark Codes
Click Here For Pokemon Hints/Secrets 1
Click Here For Pokemon Hints/Secrets 2
Click Here For GameGenie Codes For Pokemon Red/Blue Versions!!
Click Here For A walkthrough for Pokemon 2 (Gold Version), it's not complete but has a lot of information.