If you own a Wii, with BootMii. Store it safely. Never flash someone else’s NAND to your console. For Dolphin, dump your own Wii’s NAND following the same process. Deep technical insight: The Wii NAND is one of the few consumer devices with full-device encryption bound to hardware secrets (per-console AES key from OTP). Without those keys, a raw NAND dump is encrypted garbage. This is why “download a NAND” is mostly useless for running on another console – but still useful for emulators like Dolphin, which can emulate the keys if provided.