GC data is missing and Wii U will have no problem matching it
Hm... won't it? I don't know, GC TP vs. Wii U BotW feels like a far harder battle than Wii TP vs. Switch BotW.
Wii vs. Switch might as well be over at this point, with Breath of the Wild being better received (longer legs for sure), it's actually THE system-seller for the Switch (something TP never hoped to be), will still get plenty of hype with the upcoming DLC and hasn't even had a holiday season yet. Despite all of that, it's already ahead... no contest.
Wii U version on the other hands will surely have much worse legs (it's already taking a very steep decline), and whatever DLC and holiday hype the game gets will be all focused on the Switch version - that, and Nintendo's making sure it never gets too much stock. I don't think it outselling GC TP is guaranteed at all.