Get all pokemon
Beat the Elite 4 ten times and then catch Tangela under Pallet Town and then talk to Pro Oak and he wil give you every pokemon. I think.

Easy Win Against Elite 4
Have these following pokemon at these levels with these moves. Buy 10 Hyper Potions and 10 Revives and your ready to go:

Kingdra Lvl 70
Surf, Dragon Dance
Ice Beam, Hydro Pump
Porygon2 Lvl 70
Lock-On, Zap Cannon
Recover, Psychic
Togetic Lvl 70
Fly, Ancientpower
Metronome, Double-Edge
Tyranitar Lvl 70
Crunch, Rock Slide
Trash, Earthquake
Steelix Lvl 70
Rock Slide, Double-Edge
Dragonbreath, Iron Tail
Charizard Lvl 73
Wing Attack, Blast Burn
Flamethrower, Fire Spin

If you dont know, there is a guy in the Rock Tunnel who teaches your pokemon Rock Slide. Every time you face the Elite 4, you should hurt them bad with these guys.

How To Catch An Egg
First Go to four island. To access it you have to beat the pokemon league and get the rainbow pass from celio in side the pokemon center on one island. Then you breed two compatible pokemon then they will have an egg if they like each other then after you get the egg you can hatch it bygoing into icefall cave and taking 550-700 steps and your egg should hatch! Have fun getting baby pokemon. Also if you have a Ditto you can get a pokemon male/female to breed with it.

How to get Zapdos
To get Zapdos go to veridian cave after defeating the elite 4 and go to the middle and you should find a zapdos.

How to get Groudon
First go to island 7 and go into the secret cave near the picknickers and solve the puzzle then go to the ruins and go to the last one on the left and you should find Groudon.

Ultra ball into Master Ball
In battle, throw an ultra ball at a WILD pokemon. Hold B when the ball opens and drop B when the ball closes. If you do it correctly you'll get a master ball!

How to get Larvitar
Before beginning you must have the Rainbow Ticket or access to Island 7. Now head to the Island and once there head straight for the Poke Mart if you do not have any Poke Balls. Now your going to want about 5 Ultra Balls though usually you can catch Larvitar with one - though to be on the safe side bring 5. Your will also need a level 10-15 pokemon to weaken Larvitar. Once you have these items head to Sevault Canyone, if you do not know where this is on the Island check your map. Once there look around in the grassy areas. It will probably take you ten minutes to encounter him. When you see him he will be at level 15. He will evolve into a Pupitar at level 30 and into a Tyranitar at level 55. While training him remember that it takes a lot of patience to get him to evolve. Though also remeber that it is worth it for once he reaches the Tyranitar he'll melt your freakin' face!

How to get Mewtwo (with a Poke Ball)
First buy about 15-20 Poke Balls, then go through the Cerulean Cave and find Mewtwo. (if you want to find Mewtwo you must have beaten the elite four and have gave celio the ruby and sapphire for his machine.) Then when you find him you have to lower his health a lot and have paralyzed him, burned him or things like that. Then try using the poke ball and it should work.

Navigate through the lost cave on Island 5
Move right, up, down, down, right, left, down, right, up and you will arrive at your destination. Note: You can go different ways, but you will end up either finding an item or going back to the start. Use the following trick to get an egg: put a pokemon with a ditto then give it to the daycare centre then you should have a egg.

Go to the daycare man on the Sevvi Isalnds and drop off two compatible pokemon: he has to say that they are compatible and like each other then go to the Icefall Cave and wait there for a while, then talk to the man and he will have an egg waiting.

Catch a Bagon
First of all the requirements to do it:

- Water Pokemon that knows surf and waterfall.

- First go to the waterfall and go up it.

- Then go to the ladder and go to another ladder.

- Once you are there, you will battle an old couple and dragon tamer.

- Go dowm the left side, and continue and go in another ladder.

- Use surf and go into a small part of Meteor Falls whilst surfing.

- Then surf up to a small slab and look around there.

- In a few minutes you shall find your well deserved bagon.

Credits
Now this is an old tip and yes, it works in Fire Red and Leaf Green too! After your Pokemon are registered as champs, when you get to the credit part when your person walks out of the door at the league, reset or turn off and on and you'll be at Pallet Town again.

Deoxy's Puzzle
To solve the puzzle on Island 9 push the triangle from the: bottom, top, bottom, left, right, left, top, right, left, top. If this does not work the first time keep trying it for a few more times. If that doesn't work try it the opposite way: top, bottom, top, right... and so on.

Determining Pokemon's Feelings
When you use an item on one of your Pokemon outside of a battle, such as a Potion, the Pokemon will either move closer or away from you in the short intermission sequence. How far the Pokemon moves depends on how much it likes you. If it does not move at all, it feels neutral. Spread the word.

Special Recognition
Once you have collected all 200 Pokemon in this game, go to the Celadon Mansion in Celadon City and the man who is in charge of the Game Freak will give you a diploma.

Get the National Dex
Once you have beaten the Elite 4 and have more then 60 pokemon in the pokedex, go to Pallet Town and see the Professor. He gives you and Gary the National Dex, which allows you to view the entries of all 386 pokemon.

Enable trading to Ruby and Sapphire
Fix the Network Machine on Island 1. This is done by getting both the Sapphire and Ruby (in game items) and bringing them to the machine

Mystery Gift
At any time during the game, go in to a PokeMart and check the note on the desk. This will bring up a four word entry screen. Enter the phrase "Link Together With All." When finished, the cashire will mention that the Mystery Gift option will be available from the main menu after you save your game and toggle system power.