IntelliHeath
As in "Heathcliff"
Besides guest characters, Xenoblade is the first non-EAD/SPD IP introduced to Smash Bros. since Fire Emblem in 2001, so it's certainly "unique" in that sense. It stands out against Pikmin, WarioWare, Kid Icarus, Animal Crossing, Wii Fit, and so on.
Hmm, is that possible that what Sakurai referenced in his first comment in Shulk's POTD?