Transferring Animal Crossing: Wild World Save from DS to Wii - Not Possible

You cannot transfer Animal Crossing: Wild World (DS) save data to the Wii, even with an R4i flashcart.

Why It Fails:

• Incompatible Save Formats: DS (.sav) and Wii (Wii Save Data / NAND) use completely different structures and encryption.
• No Cross-Platform Tool: Nintendo never released a transfer utility. The R4i only runs DS homebrew/ROMs on DS hardware—it cannot interface with a Wii.
• Wii Version Is a Different Game: Animal Crossing: City Folk (Wii) is a separate title with different data structures (town layout, items, villagers).

Alternatives:

• DS-to-DS Transfer: Use the in-game "DS to DS" option (requires two DS systems and two carts) to move your town to another DS cartridge.
• Homebrew Backup (DS): Use Checkpoint or GodMode9 on a hacked 3DS/DSi to back up the .sav file to SD card. You can then use it on an emulator (melonDS, DeSmuME) on PC.
• Start Fresh on Wii: City Folk lets you create a new town; some items/villagers reference Wild World but no data carries over.

Warning: Unofficial "transfer tools" claiming DS→Wii are scams or malware.