What to do after elite four in Pokemon LeafGreen?

Answer 1

After you beat the elite four your character will be at home and there will be a news report on tv. It will say a rare Pokemon has been sighted in the region. Then Norman will ask what kind of Pokemon it was and the player will choose either red or blue. If you choose red Latias will appear in the wild, if you choose blue Latios will appear.

Also after defeating the elite four, you can go to the Battle Tower in Ruby and Sapphire. In Emerald you can go to the Battle Frontier.

Answer 2

In my Fire Red after the elite 4 (you have to own at least 60 pokemon) talk to Proesser Oak and he will tell you to talk to The guy who gave you the ticket to island 1-3. that guy will give the ticket to island4-7.

Answer 3

I would suggest if you have not caught Articuno/Zapdos/Moltres catching those first as their data will be used later.

If you have not yet completed Islands 1-3 (you should have caught Moltres if you have completed Island 1). Do so.

Next: Make sure you have 60 Pokemon in your Pokedex (caught which is why I mentioned the data earlier). Head to Pallet town and Oak will give you the National Pokedex.

Travel to Island 1, and Bill/Celio will give you an errand which involves Islands 1-7. The Ruby can be found on Island 1 (the Rockets you saw on Mt Ember guard a base), the Sapphire you must first beat the Rockets on Island 4. (You will see Lorelei here and she will then return to the Elite 4). Then head to Island 6 and head South opening the Dotted hole with cut. Head through that area using the Braille to tell you the correct hole, after that you will be prompted to head to Island 5. Defeat the Rocket base there and then head back to Celio. You can now trade with Ruby, Sapphire and Emerald (as well as XD/Colo, although Box requires 100 Pokemon in your Pokedex).

You can now rematch the Elite 4.

(I was vague on the Islands to avoid Spoilers)

Answer 4

You'll get a ticket for a ferry from vermillion city to a cluster of islands. The adventure continues...and get more pokemon.