Heh. You can get Punchout without an action replay, already.

After analyzing the password system, a gamefaqs board user was able to determine about 150 possible NES codes for telling nook for himself. He stumbled across a working Punchout code in these 150 combinations.
You must create a new town on a new memory card for this, unless you want to start over.
First, create player

sp)Lao
That player name is a single space, then Lao
Create Town: Tzu
Then, after running errands, go to Nook and say this code:
3Ec5za9xYcxkLm
yYR9ry0z%ucJ6V
Nook will give you a present containing the NES game Punchout! Now, stick the memory card with your original town data in slot B, and hop a train to your actual town that you play in. Drop the Punchout game in front of your house in your normal town, then head back to Tzu. Save, quit, load your regular town, go outside and pick up punchout, bring it into your house, drop it, and enjoy!