There's 3 stickers you can collect: Hall of Fame sticker, Egg sticker and the Victory sticker. The hall of fame sticker will be given to you when you defeat the elite four and the Pokemon champion, the egg sticker will be given to you when you hatch a Pokemon egg, the victory sticker will be given to you when you defeat a friend in a link battle.
You have to beat the Pokemon League.
you beat the elite four
Yes you can trade leafgreen version Pokemon to another leafgreen version.
You get trainer stars by completing in-game task. You must complete the Kanto Pokedex, national Pokedex, enter the hall of fame, 200 jumps in the Pokemon Jump, and collected 200 berries in berry picking.
Gary until you beat him and then you get put into the hall of fame and you become champion
beat the Pokemon league
There is no such thing as a main hall.
There's 3 stickers you can collect: Hall of Fame sticker, Egg sticker and the Victory sticker. The hall of fame sticker will be given to you when you defeat the elite four and the Pokemon champion, the egg sticker will be given to you when you hatch a Pokemon egg, the victory sticker will be given to you when you defeat a friend in a link battle.
You have to beat the Pokemon League.
after beting your rival in curulian city
pokecommunity
beat elite four
You have to enter the Hall of Fame.
you beat the elite four
You must deliver the Ruby and Sapphire item to Celio at the One Island pokemon center in Leafgreen first. Become part of the Hall of Fame in Sapphire next. Now you can trade anytime, go upstairs in a pokemon center and talk to the lady who leads you to the Trade Center (middle lady for sapphire, right lady in leafgreen). Link up and you can start trading.
Here was my method: Using a Gameboy game register at least three pokemon at level 100, for the other 3 party members select any of the rental pokemon that you need in the hall of fame. Finish the Elite Four as normal and all the pokemon will be registered in the Hall of Fame. Repeat this until you have all the entries.