Be interesting if on the eventual Vita version if they mapped the second player stuff to the back touch of the Vita. Have some real pat your head and rub your tummy stuff going on there.
If they ended up doing that, they'd have to change the mechanics a bit so that just tapping on the back touch activated whatever you
could normally interact with next. I've played Vita games like Escape Plan that use the back touch for precision and timing-based puzzles, and it's just too hard to consistently hit a precise spot on the back touch.
Honestly, though, I'd rather they just scrapped the silly Wii U co-op option for the other versions. It was designed for the Wii U controller, even if I
did buy the Wii U version I'd never have anyone to play Co-Op with (I don't live with anyone who games), and it's just not a feature I care about. I'd rather have online Co-op for the other versions.