Foster J.
Smash Ace
Interesting bug huh?
So in essence, this works on all but the heaviest of characters in which case the weight difference would reduce the knockback slightly so they'd be hit by the 2nd hit at 0 % and thus not thrown into the blast zone.
Posted from
http://www.reddit.com/r/smashbros/comments/2v62xe/someone_explain_this_toon_link_instant_ko_at_0/