I went to check if any H!P songs were recently added to Wii U karaoke and, randomly enough, ... they have added this song from ex-Egg Sayaka Kitahara:
So Wii Karaoke U hasn't got a single Berryz Kobo song so far, but they have a five year old Sayaka Kitahara song. It does have 228,000 views on YouTube, but Berryz songs were also cracking 500,000 views, so... o-o;;