For me, Cresselia for some reason lol I always have to think for a moment after hearing its name --- http://25.media.tumblr.com/tumblr_mdtqd6EJTY1qlpahho1_500.jpg My husbando <3 QWILFISH for Smash 4! Also waiting on Qwilfish's Megalution, QWILSHARK!
Victini does get points for being at the start of the region's dex instead of the end, so I do sometimes forget it when mentally going through the list. But I think my answer goes to Heatran. That thing could have easily been a normal single-stage Pokemon. Hell, it even has a gender. And unlike other legendaries that don't have much of an impact on anything (the Lati duo, for instance), it isn't part of a group, it's just kind of its own entity. --- If you actively hate Justin Bieber... then you don't know what "intended audience" means. Hate Twilight instead, it's far worse.