Here is the list of Pokemon games that have tricks in them. They are tricks because they are glitches in the game and codes are things that would cheat for you (i.e. Gameshark) I will eventually get the gameshark section up and running but for now, heres the list of tricks. Please also note that I will tell you if the trick may be dangerous to your game and I will only put up tricks if they are to work.
Pokemon Red/Blue Tricks
Pokemon Red and Blue Version Tricks
Find Safari Zone Pokemon on Cinnabar Island
Useless Tricks in the Game