it's true. My brother was using kirby and my room mate was using luigi. When luigi had 150+ damage he did his final smash and my brother thinking that if he downB on him in the air, he would kill him but it did nothing.
I really should start video taping my matches, I actually have air tripped with bowser with 3 other people around. it was clear as day since when he air tripped he looked like he was facing away from me with his arms and legs spread out and spun slightly, almost like being footstooled.
I'll try to find a way to record these fights.