No.
On Pokemon Pearl's title screen, if the Pokemon LeafGreen game is in the GBA slot, click on "Transfer From LeafGreen" and you can choose six Pokemon from LeafGreen to transfer to Pearl, but be careful-you can't trade them back.
Transferring GBC games to GBA games is impossible.
You will only need to beat it if you want to transfer pokemon from the games Ruby, Sapphire, Emerald, Pokemon Colosseum and Pokemon XD Gale of Darkness. You can transfer pokemon immediately to another leafgreen or a firered version using either the GBA link cable or the Wireless Adapters.
you should get one in Pokemon firered/leafgreen/ruby/Sapphire/emerald and transfer it to gba via pal park.
Migrated Pokemon are the ones you can catch at Pal Park after you transfer them from FireRed, LeafGreen, Emerald, Ruby or Sapphire games for the GBA.
Yes, but not directly. You need to transfer your Colosseum Pokemon to a Game Boy Advance game (Emerald, LeafGreen, etc.) with a GBA-Game Cube link cable and then transfer the Pokemon from the GBA game to XD with the same cable.
you cannot clone Pokemon in firered/leafgreen. the only gba game you can nlone in is emerald.
after you get the national pokedex, you need to insert a GBA game like firered or leafgreen, in the start menu, you choose migrate from GBA or migrate from "choose the color of the game (leafgreen, firered, ruby,...)". Then you choose six Pokemon from the GBA game, you'll transfer them to platinum. Carrying these Pokemon, you'll be able to enter pal park and catch Pokemon in various locations.
use a GBA Gameshark to get item event
Go upstairs in any Pokemon center hook up a wirless adapter to 2 GBA's or GBA link cables trade with a leafgreen and have leafgreen trade you there starter Pokemon.
543.5667.123. enjoy
if you have an AR for the gba