So far, the item and weapon leaks that have occurred have actually come from a NeoGAF user, who has actually taken screenshots of the Nintendo Switch version, as well as cropping the icons for the items and such. I wonder if it could be someone who works for PrimaGames?
Either way, no one has the Wii U version except for Nintendo themselves.
Nintendo posted the EUR version to NUS a few days ago. They removed it soon after. However, the TitleID's for all of the regions have been leaked and, it's rumored that someone has a copy of the Wii U version that was downloaded while it was on the NUS servers but, that cannot be proven at the moment.