Instructions
Travel to Route 15 after receiving your National PokéDex in "Pokémon Black" or "Pokémon White." You'll find an orange and blue building called the PokéTransfer Lab.
Insert a Pokémon Diamond, Pearl, Platinum, HeartGold or SoulSilver cartridge in which you have Charizard into a second Nintendo DS and connect the two devices together. If you don't have Charizard, you can send over Charmander or Charmeleon and train them in White or Black until they evolve into Charizard.
Enter the Lab in "Pokémon Black" or "Pokémon White" to begin the transfer. PokéTransfer will connect you with your second DS and allow you to choose up to six Pokémon to transfer over. Select Charizard and any others you want to transfer. After your selections are made, a mini-game will begin.
Shoot Pokéballs at the Pokémon as they scamper around the screen and hide in bushes. You need to hit each of the transferring Pokémon within the time limit in order to transfer them into "Pokémon Black" or "Pokémon White." If the time runs out, any uncaptured Pokémon will return to your older game. Try again until you can capture your Charizard. When the game ends, and Charizard is captured, he'll be added to your Pokemon inventory.