So I had Warioware DIY on my DS, and decided to get the companion channel: WarioWare DIY Showcase. I had it on my old Wii, but I sold it since and I want it on my Wii U (in vWii mode).

So I search for the WAD on google, and I can only find the USA version (which is fine, since I own the USA version of the DS game). Then I tried installing via Multi Mod Manager, and it says:
Status: 1 did not complete.
Then I try to install using YAWMM (Yet another WAD manager mod) and it installs just fine. Stupid idea, as when I launch the channel, I get a message saying “This channel cannot be used.”
Fortunately, I didn’t brick my vWii, but that was still a dumb decision.

Next: I try NUS downloader. I try the USA, EUR and JAP titles, and I check the box that says “Pack WAD” but for every one it says “Error packing WAD” and “404 error: Could not be found on remote server” and “This title has no ticket and cannot be packed/decrypted” and other similar things.

So I finally decide to buy the stupid title again. I launch the Wii shop channel, only to find since March 25th you couldn’t buy any more Wii points as the Wii shop is closing soon.

That sucks.

Can anyone please help me successfully install WarioWare DIY Showcase?

 

Because if it doesn’t install with MMM, it probably has a good reason. So a brute-force install is probably not the best idea.

 

A black screen probably indicates a video format mismatch. On your Wii try changing the video signal to NTSC and see if it works. (I don't think this is safe or even possible on the Wii U)
Before you try anything, have you tried running the WAD on Dolphin? If Dolphin runs, then you're rid of the possibility of getting a faulty WAD.