There is a glitch or trick that i can not remember i dont remember what version it is on but all i remember is that it has to do with the passed out man that teaches you how to get pokemon in viridean city.
Talk to him and when he asks if you're in a hurry, say "no." After he shows you how to catch a Weedle, fly to Cinnabar Island and surf up and down the edge until Missingno or M' appears. Leave the battle and you will find that you now have well over 100 of the sixth item in your pack.
Go get the coffee he asks for, by pouring it on his head. Then he'll get enraged and send L132 Missingno. after you. Ooh! A Pokemon! Why not fight it, catch it, or at least take advantage of the fact that you now have an extra 128 copies of item 6 (unless you already have 128 or more)?
That or you get so fed up with his hand-holding "OMG this is how you throw a Poke Ball!" lesson that you run, fly, bike, and/or swim all the way to Cinnabar, where for some reason the Vulcan Mind Meld he performed on you a short while earlier (such that you saw the battle first-person from the Old Man's perspective rather than your own) has left traces of your own identity in the air all throughout Kanto (how else could you know what to return to after the mind meld is over?), and and the east coast of this island is one of very few places where you can observe the warping effects of your identity on the wild Pokemon around you, without disturbing the atmosphere and having it dissipate such that only "normal" Pokemon appear.
Take your pick between those; I'm not sure which it is.