EFB to RAM is only necessary for certain menus and the World Map to look right. If you can deal with those (I did, for 50 hours of gameplay 
) then I second delroth's suggestion to use EFB to Texture.
Keep in mind that NullDC is a DC emulator, not a GC emulator, and certainly not the Dolphin emulator. What works in one emulator doesn't necessarily apply to another. Not only are they using different code to emulate different hardware, the game code (the actual assembly instructions on the discs) is going to be different between the DC and GC versions.
) then I second delroth's suggestion to use EFB to Texture.Keep in mind that NullDC is a DC emulator, not a GC emulator, and certainly not the Dolphin emulator. What works in one emulator doesn't necessarily apply to another. Not only are they using different code to emulate different hardware, the game code (the actual assembly instructions on the discs) is going to be different between the DC and GC versions.