DivineDeity and SaturnGamer going toe to toe... it gets me every time. xD
In all seriousness, I've never really looked into the idea of a Yuyuki character before, but if you think about it, it'd definitely be a
'wtf character' in the most traditional sense possible - a retro character that nobody considered fit for revival. Granted, there's been a precedent set for it now, but back in the Melee days, the inclusion of Ice Climbers was a legitimate surprise and it'd be nice to see something on that kind of level again... even if it is but a pipe dream.
Plus, again, Nimbus cloud. Bonus points if the Nimbus cloud can be taken and used by other characters like a Lakitu cloud in Mario.