The only downside is that the code is not universal. I still have it in my saved game though.
METHOD 1: For those with a spare memory card
Start a game with the following names:
Character: (space)Lao
Town: Tzu
After you do the errands, tell Tom Nook this code:
3 E c 5 z a 9 x Y c x k L m
y Y R 9 r y 0 z % u c J 6 V
Then just travel to this new town with your old character and pick the game up, whether through Lao's gyroid, or just leaving it on the ground.
METHOD 2: For those with GBA link capabilities
Turn the game on without any memory cards, and just start without saving.
Start a game with the following names:
Character: (space)Lao
Town: Tzu
After you do the errands, tell Tom Nook this code:
3 E c 5 z a 9 x Y c x k L m
y Y R 9 r y 0 z % u c J 6 V
Then, go to your GBA island. Keep talking to the islander until the islander offers to buy Punch-Out from you. Save the island, then load your regular town. Go to the island and keep talking to the islander (it might take a LOT of talking) until they give you Punch-Out.
1 down, 4 to go. People at the gamefaqs message boards are working hard on cracking the code to get passwords for Legend of Zelda and Super Mario Bros. before Nintendo releases them. And sorry, you can't transfer Punch-Out to the GBA's flash memory.