Pocket Monsters Emerald

You can go to Altering Cave after you beat the Elite Four. It is located on Route 103.

After beating the Elite Four, a new part of Meteor Falls opens up. It is in the northwestern corner where you found Iron Tail. A new cave was made and you'll find Steven in it. His Pokemon are in the high 70's.

Tell the Berry Master's Wife certain phrases to receive the following berries. You can only tell her one of these each day.

After you defeated the Elite Four, go to the Upgraded Safari Zone. In the Safari, you can catch some GSC Pokemon such as Houndour, Aipom, Stantler, Mareep, Miltank, and more GSC Pokemon. This Unlockable works only in Pokemon Emerald.

If you have a Pokemon with Compound eyes 1st in your Party it will drw Wild Pokemon that has held Items more often.

Have a Pokemon use CUT to remove grass where wild Pokemon live. It will remove the chance of encountering wild Pokemon. The grass will regrow once you leave the area or enter a building.

Simply put a pokemon with the ability Flame Body or Magma Armor on your team to cut the amount of steps needed to hatch an egg in half.

To get the old rod, go to dewford town and talk to the fisherman near the gym. He will give you a old rod. To get good rod, talk to the fisherman on route 118, east of mauville city. You must need surf to reach him. Talk to him and you will get good rod.
To get super rod, go to mossdeep city and go north of the space center and go into the house. The man inside will give you super rod.

In one of the treehouses in Fortree City is a man with a Wingull. Talk to the Wingull, and it will fly off out of the treehouse. When you get to Mossdeep City, you will see a person with a Wingull. Talk to it and it will fly off as well. Then go back to Fortree City and into the treehouse where you talked to the first Wingull. Talk to the man next to the Wingull, and he will give you the Mental Herb, and item which is a hold item that prevents attraction on the Pokemon that is holding it.

After you defeat the Elite Four, go to your house and watch the television downstairs. After you watch it, your mom will ask you what color the Pokemon is. If you say Red, you will find Latias. If you say Blue, it will be Latios.