I did the system update 5.0 yesterday and now all Wii games are displayed with a pink and green hue. Wii U games work properly and have the correct color. I called Nintendo's "Tech Support" and talked to a very nice girl who, unfortunately, didn't know what she was talking about. She said that other people have made the same complaint about the pink/green color to Wii games after the last system update. Then she had me change the resolution setting on the Wii U gamepad from 1080 to 480, which only made the screen pixelated and blurry. Not sure how resolution would fix a color problem, but whatever... Then she told me I would need to send my Wii U in to get it repaired! I told her that this is obviously a problem with the system update and not with the Wii U console, but she insisted this was the only way to fix the problem. I told her that is ridiculous and I'm not sending my Wii U console in for "repair".
I love my Nintendo games and I have stood behind the Wii U, but the Wii U has been headscratchingly problematic since day one. Hopefully, there are real engineers working for Nintendo who can fix this color problem on the next system update. The "Tech Support" seems to be made up of youngsters who simply put you on hold while they see if they can find the solution to your problem in the Wii U Troubleshooting section of the manual.