Duplicate Pokémon

Chance of mess up your game: Very likely - use with caution! Set up a trade with the Pokemon that you want to be duplicated and any other Pokémon that you don't want, becuase it will be erased. For example, if I wanted to duplicate my Mewtwo, I would set up a trade with a friend and trade Mewtwo for anything else, preferably something they don't want. Near the end of the trade, the screen shows "Waiting..." then "Trade Complete!" When it says "Waiting," turn your Gameboy (the one with the Pokemon you want to duplicate) off when the "Waiting" screen disappears, do it quickly. Then the other Gameboy will say "Trade Complete," this is when you turn that one off. Now you will both have the Pokemon.

 HOW TO GET YOSHI
To get the hidden "Yoshi" pokemon you need two players who both have beaten the game and have all 150 pokemon.

1.) The Blue version player trades the Red version player for a Dratini.

2.) The Blue version player then gets Dratini to a Dragonite and gives it back to the Red version player. Then the Red version player heads to the basement level of the Unknown Dungeon and surf closest to where MewTwo is/was. Then he/she uses a Fire Stone on the Dragonite.(Notice "Not Available" will appear but still select it.)

3.) The screen will glitch, and the Dragonite will evolve into "Yoshi".

4.) This Pokemon will have the stats and name of Dragonite, however it will have Yoshi's pic and will be No. 999. All you have to do is rename it as Yoshi.
 CHRONA MEW
Mew can evolve into Chrona Mew. Go to the Seafoam Islands and use the Itemfinder to locate the Mist Stone. There is only one, and is very difficult to find.

 PokeGods
There are such things as pokegods. To get them beat the Elite Four 30 times without talking to anyone in between the nurse in the pokecentre at Indigo Platue or what ever it is, and the riv . On the thirtith times
Professer Oak will say "I'm getting tired of this" and he will let you walk around the hall of fame which leads to a new city where people will swap pokegods.
 Ice Stone, Pikablu and Flarachu
Get 7 Level 100 pikachu's an itm finder rock tunnle* mount moon use the item finder a few times ull find an item called the 1 the only the "Ice stone" u can use the ice stone as many times as u want like a "HM" to evolve pikachu use the ice stone once to evolve Riachu use it twice *** when using cheat in rock tunnle don't use flash***
 Togepy
all you do is use the item finder in mt. moon 100 times (make sure that it is all in different places, or it doesn't work)and on the 101 time it will respond. when you find the item it will be an egg. after you play long enough the egg will hatch and presto! you have a togepy!

 *Fighting Level 135+ Pokemon:
Do the Missingno code above, ignore Missingno if you see it. Then you'll start seeing level 135+ pokemon. If you're lucky, you might even see a bulbasaur, squirtle, or charmander.
 Get a Level 50 Togepi:
You must do this code right! First you must beat the Elite Four 9 times, without losing once, then go to Prof. Oak and he will tell you to go to the Power Plant. Go to the end of the Plant where you caught a Zapdos. You will see a man standing there, go to him. The man will be Brock, the first gym leader you faced. Then he will talk to you for a while telling you about an unusual pokemon and then he will tell you to fight him to get it! If you beat him you will recieve a Level 50 Togepi!
  Invisible Computer?
In Celadon City, go down to the house in the right hand corner. Inside there should be a hotel with a few people walking around. Go inside the hotel. Go all the way to right side of the hotel, go all the way down, and go one spot up, and hit A. If nothing happens, go up one more and hit A. Just watch out, because you could unknowingly walk right through the computer.

 Defeating Brock
Catch a Caterpie in Viridian Forest. Advance it to level 7 and he will evolve into a Metapod. Advance it to level 11 and it will evolve into a Butterfree. Butterfree can beat JR. Trainer and Geodude. Butterfree will have to be at least level 13 before it can beat Brock. Note: Use your Pikachu's tail whip to lower their defense.

 MissingNo.

Chance of messing up your game: Very Likely, known to restart game or mess up saved game. Go somewhere where you trade Pokemon with a computer trainer. A good place is Cinnabar Island Lab... there are lots of people to trade with. Trade with anyone, then go outside and swim on the left shore of the island, where you are swimming on half-land, half-water. Keep on swimming up and down, and you will run into MissingNo.