Pokémon FireRed and LeafGreen/Secrets

Shiny Pokémon
Every time you encounter a Pokémon, you have a 1/8192 chance of the Pokémon being a different color. The Pokemon will look "Shiny". This will not affect its stats, but it sure looks pretty.

Determining Pokémon's feelings towards you
When you use an item on one of your Pokémon outside of a battle, such as a Potion, the Pokémon will either move closer or away from you in the short intermission sequence. How far the Pokémon moves depends on how much it likes you. If it does not move at all, it feels neutral. You can also take your Pokémon to Daisy in Blue's house and ask her.

Free Coins
In the Gamecorner in Celadon City, go talk to the man at the far right Slots. He will give you 20 free coins. Talk to the man on the slots beside him. He will give you 20 free coins, also. Go to the left side of the Gamecorner. Talk to the guy that looks like a fisherman, and he will give you 10 free coins. There are also hidden coins on the ground so use the Itemfinder or press on every tile. If you find them all, you'll find 200+ coins!

Itemfinder Secrets
There are places in the game where important people/Pokémon have stood at one point. If you use the Itemfinder on the EXACT spot where they were, a special item will be found which is usually very rare. You cannot find these items any other way.

How to unlock:
 * Leftovers: Use Itemfinder where the 2 Snorlaxes appeared.
 * Macho Brace: Use Itemfinder where Giovanni was in Viridian Gym.
 * Soothe Bell: Use Itemfinder where Mr. Fuji was standing in Pokémon Tower

Three Unique Moves
On Two Island, a rare Move Tutor lives on the north of the Island. She will teach your starter Pokemon one of three extremely strong moves: for Venasaur,  to Blastoise, and  to Charizard.

Lorelei's Doll Collection
For every 25 times you enter the Hall of Fame, Lorelei will add a new doll to the collection in her house on Four Island. She'll stop after adding a total of eight dolls.

Unlocking Mini-Games on Two Island
When you have access to Two Island, save the Game Corner owner's daughter, then deliver the package. The grateful owner will open some mini-games that you and your friends can play wireless. More info will be found on the Two Island page.

Free Nest Balls
There's a woman that lives along the Water Path that's looking for a. If you catch one and bring it to her, she'll measure it and give you a Nest Ball as a reward. Each time you bring her a taller Heracross, she'll give you another Nest Ball.

Trainer Card Stickers
Four Island is home to a Braggart. He will ask you what you want to Brag about, and award you a sticker, depending on the achievement that the player has accomplished.

How to unlock:
 * Egg Hatching Sticker: 1st Lv Hatch 1 Egg.
 * Egg Hatching Sticker: 2nd Lv Hatch 100 Eggs.
 * Egg Hatching Sticker: 3rd Lv Hatch 200 Eggs.
 * Egg Hatching Sticker: 4th Lv Hatch 300 Eggs.
 * Hall of Fame Sticker: 1st Lv Beat the Elite Four, 1 time.
 * Hall of Fame Sticker: 2nd Lv Beat the Elite Four, 40 times.
 * Hall of Fame Sticker: 3rd Lv Beat the Elite Four, 100 times.
 * Hall of Fame Sticker: 4th Lv Beat the Elite Four, 200 times.
 * Multibattle Link Win Sticker: 1st Lv Win 1 Battle.
 * Multibattle Link Win Sticker: 2nd Lv Win 20 Battles.
 * Multibattle Link Win Sticker: 3rd Lv Win 50 Battles.
 * Multibattle Link Win Sticker: 4th Lv Win 100 Battles.

Easy money
On Five Island, there is an area to the northeast named the Gorgeous Resort. In this are there are 2 very wealthy trainers you can face, named Lady Jacki and Lady Gillian. Lady Jacki will award you 10000 if you beat her, and Lady Gillian gives you 9800.

The Pokémon they use also carry expensive items. Jacki's two Pokémon carry Stardust, Gillian's two Mareep have Stardust, and Gillian's Flaafy has a Nugget.

Combine the use of VS Seeker, a Pokemon holding the Amulet Coin, and that knows the or  moves, and each time you battle these two trainers will exponentially increase your money!

Legendary Beasts
In FireRed and LeafGreen you can get the 3 Legendary Beasts, depending on your starter Pokémon. The player must: 1. Beat the Elite Four 2. Complete the Ruby and Sapphire side-quest 3. Find the Beast in the tall grass of the Kanto region. Its location will be random. The Beast to be caught will have a type advantage to your starter Pokémon.

WARNING: There is a glitch in the game and if you let the Pokémon use on you, it will disappear from the area section on the Pokédex and you will never see it again.

Unlock Trading to and from Pokémon Ruby, Sapphire, and Colosseum
At the beginning of LeafGreen/FireRed, you can only trade between these two versions. However, if you complete a certain quest in the game, you can then trade to Pokémon Colosseum on the GameCube, and Pokémon Ruby/Sapphire, the two other Pokémon games on the GBA.

Defeat the Elite Four, then retrive both the Ruby from Mt. Ember and the Sapphire from Team Rocket, then give them both to Celio.

Saving Time in the Safari Zone
When the player is in the Safari Zone, the amount of time left is determined by the number of steps taken. A player can "roam" the grass, without adding steps to the counter by entering the grass, then lightly tapping the directional pad in a different direction.

This will change the way you are facing, and may trigger a Pokemon encounter, but it will not count as a step for the time counter. This can be helpful to catch particularly rare Pokémon, such as. In addition, if the player brings a Pokémon that knows, the move can be used to trigger encounters without moving.

Unlimited Nuggets
On the bridge on Route 24, above Cerulean City, there are five trainers that you must beat to cross the bridge. At the end, a Team Rocket Grunt congratulates you for defeating everyone else by giving you a Nugget.

If you lose the battle against the Grunt, you will faint and re-appear inside the Pokémon Center, but you will still have the Nugget in your Bag. When you go to cross the bridge again, the whole conversation will reset, and he will give you another Nugget and fight you again.

You can lose the battle yet again, and repeat this as many times as you want. Nuggets sell for 5000 each!