Valentines Chocolate looks to be either:
A) time-based, where it bounces once and comes out
or B) Like Platinums presents, where it triggers if the opponent stands over it after it lands and becomes active.
I think B is more likely - I was thinking it might also be a kind of counter because it seemed to jump back when Naoto used an attack, but I managed to pause on a frame in the vod before Naoto's attack came out and she was just crouching, yet the present had already bounced back (and Marie was in the animation for her evasive action, so I doubt she could have used it as a follow-up command)