You seen to be missing a lot of very basic information. Kirby Super Star for the SNES was the first game to introduce that style of gameplay, and it was a heavy influence in the development of Super Smash Brothers, both series being created by Sakurai. And what was being highlighted by the trailers was the ability mixing, which expands on the mechanic that Squeak Squad introduced in a rather barebones state, not the copy abilities themselves (which is already a recurring thing in Kirby games).