If your pokemon are in bad shape, and the last thing you need is to bump into a wild pokemon. Then you can use CUT to hack through tall grass and avoid wild pokemons. Very useful.
100 Casino Coins
In the gamescorner, there sre 3 machines that you can't use. If you visit each one (from left to right, without going to any others), then go to the shelves in the upper right hand corner, and the 3rd shelf from the left will have 100 coins!!!
Level 100 Pokemons
This code will only work on the japanese versions
PS - Your pokemon's HP and Health bar may be messed up but it can be fixed
once you go to an Pokemon Center
Pokemons at Level 149
First go to viridian city and talk to the old man who teach you to catch pokemon. Then fly to cinnabar and surf up and down the coast (where it looks like your on land). Wild pokemons will attack at level 149 and you can catch missingno too!
Doubling a Pokemon
To double a pokemon find a friend who wants a pokemon you have and trade the pokemon he wants for a low level pokemon (eg. Pidgey ). The trading will be done and then it will say WAITING... then go blank for two seconds them say TRADE COMPLETE. Shut off the gameboy that traded the pokemon you want to double (eg. Kangaskhan ) right when it goes blank in between WAITING... and TRADE COMPLETE and the game will freeze on the other gameboy. Turn off the other gameboy and when you turn them back on you will find that both gameboys will have the doubled pokemon (Kangaskhan) but the other pokemon (Pidgey) will be gone.
135 Master Balls
Put Master Ball in the 6th slot from the top of items list (if you do not know how, use select on the item to move, then select on the place where to move it). After a trade, surf on the right coast of Cinnabar Island w/o going into any other fights. Missingno. will appear (no. 000) and after he appears run. You should now have a lot of Master balls( it will say nine but you actually have more [just toss them to see] ).
Get 99 of Any Item
First, return back to Viridian City and talk to the man who taught you how to catch a Weedle (he is near the Gym where you face Giovanni).Reply "No" to his question, then watch him catch a Weedle. Then, place the item you want 99 as number six from the top (we recommend the Master Ball if you still have it). To switch items, press Select while pointing to an item, then move the arrowwhere you want the item to goand push Select again. Both items will switch places. Now, FLY back to Cinnabar Island and start SURFING along the east coast of Cinnabar. You will face a messed up Pokemons, with a name comprized of symbols. Defeat him or run away but do NOT capture it. When it is defeated, you will have over 99 of the sixth item on your list! If youwant to repeat this trick, you'll need to talk to the man again. This trick also works when you capture Missingno. If you continue to surf along the coast, you will face Pokemon that are Level 175 can give you 3000 whopping Exp. Points!
Get 99 of Any Item
First, you make rare candy the 6th item on your list, then you fly to viridian city and talk to the guy who shows you how to catch a weedle, when he askes if you are in a hurry say no. After he shows you the weedle thing fly to cinnibar island and swim up and down the right shore where you are on land and water holding 'A' a wild 'M will attack, he is level 0 so dont try to catch it. Run and when you look at your items, you will have 9 rare candy with a symbbol next to it! Use it over and over and if you run out, do the trick again!
Talk to Bill when he is still a pokemon. When he steps into the pod, leave before he comes out. Fly to Cinnabar Island, and surf on the right coast. You'll eventually meet mew.