Emulator

EDIT: I have now tested this on 5.0-1323 and the same issues remain. Also, the UI doesn't appear during races at all on Luigi Circuit and similar, I was wrong on that.

Tested on a system with an Intel HD Graphics 515 (Intel Core m5-6Y54) on Arch Linux with Mesa 13.0.1, my only other Vulkan-capable system (although too slow for actual viable play of the game even at 1x IR), and the issues do not occur, so this is a driver-related issue. Haven't had any other issues with the AMD Radeon with games in my collection on Vulkan though so far.

The one on NVIDIA cards is the fourth with the diagonal missing part of the "Online not rated by ESRB"

I'm on 5.0-2699 using Vulkan and I'm not experiencing any of the issues mentioned, should this be flagged as solved?

GPU: AMD Radeon R9 280 @1072GHz + 3GB GDDR5 VRAM @1250GHz
CPU: AMD Athlon X4 860k quad core @3.7GHz

While I don't have access to the system currently to check on the latest version (will be able to check in a few days) on 5.0r2670 with Mesa 17.0, the issues persist with RADV on this game.

I reported the same issue here (sorry about that):
https://bugs.dolphin-emu.org/issues/10131

And create a bug report here (with a few fifo files):
https://bugs.freedesktop.org/show_bug.cgi?id=100430

I think we can likely close this out, unless there are issues with AMD and Vulkan.

A) The Wii Remote "please have a wrist strap attached" screen is in reversed colors.

I can't confirm. It renders correctly for me using 5.0-6004. Maybe a NVIDIA vs AMD issue though?

B) On many tracks (Luigi Circuit, for one), there is a frosted square in the top left of the screen (occurs on any internal resolution) and heavy distortion. The start menu and minimap will not appear when this is happening.

This sounds a lot like the "Blue Square" issue, that was recently resolved by forcing "Ignore Format Changes" to Off.

I still have the reversed color issue and frosted square in the top left on the same AMD Radeon RX 460 on Arch Linux, now on kernel 4.14.10, and Mesa 17.3.1 3D drivers on 5.0-6106. Will rebuild and recheck in a few hours.

Just out of curiosity, I tried this with the alternate amdvlk drivers (version r7.a20e789 ) released recently to the RADV vulkan drivers I'd been using and the Wiimote wrist strap screen displayed correctly... and then a black screen for the rest of the session followed by a crash when I stopped the game. Those just crashed on any game I tried them on in short order (especially on close.)

I can confirm the reversed color issue and frosted square in the top left with mesa 17.3.2 on ArchLinux with a R9 Fury

Untested, but this issue will likely be resolved by updating to later versions of the Radeon Vulkan Driver(RADV).

Ticket for this issue was marked RESOLVED FIXED in https://bugs.freedesktop.org/show_bug.cgi?id=100430