Do You Need Action Replay for Nintendogs?

No. Nintendogs (and Nintendogs + Cats) is fully playable without any cheat device. All content unlocks through normal gameplay:

• Breeds: Earn trainer points → unlock new breeds at kennel.
• Items/Toys: Buy at shops, find on walks, receive as gifts.
• Competitions: Obedience, Agility, Disc — win to unlock higher tiers.
• Interior/Exterior: Renovate house, change kennel theme.

Why Action Replay Is Unnecessary & Risky

• Save Corruption: Bad codes brick the save file (no cloud backup on DS).
• Online (Defunct): Nintendo WFC shut down 2014 — no ban risk, but no benefit either.
• Game Design: Progression is the gameplay. Skipping it removes the purpose.

Legitimate "Cheats" (Unlockables)

• Fireman Hat: 11,000 Owner Points.
• Gold Pedometer: Walk 50 km total.
• All Breeds: ~50,000 Owner Points (varies by version).
• Secret Items: Find on walks (rare), receive from neighbors (Bark Mode / StreetPass).

Enjoy the grind — it's the game.