is it PSO Wii to WiiU?
GCMM is for gamecube games, not wii/wiiu games.
If it's a gamecube game, it's for nintendont?
then there's no conversion needed.
nintendont (wii) to nintendont (vWii), it's the save gcm file on your sd or usb.
if you created a new memory card image instead of using the existing one (why?), then apparently you need GCSerial.exe to copy the header from one to another card.
or use latest version of gcmm to copy savegame into another memory card image, which work with header protected games.
or maybe even try Dolphin's memory card manager.
but, really, why not just use the existing memory card file? no need to merge or move data from one to another file.
if it's not detected, rename the card based on the option you are using, or change the option.
nintendont has two option for memory card : global card for all games, or one card per game (based on the game's titleID).
PS: I merged your identical threads posted at different place of the forum.
Why not use the official thread where you already asked the same question already ?
Why post this to 3 different places? it won't get you the answer faster. please, don't multipost.
it's counter productive to post the same question multiple time at multiple places, users help will only conflicts and you'll have to juggle with both suggestions and users will provide duplicated help, etc.
please keep only one thread per subject.