You can definitely use KO Punch in the air. -_-;Yeah, i'd even argue that Little Mac doesn't need it. All it does is strengthen his ground game (unless you can KO in the air which would be news to me) and that doesn't need any help. It doesn't help that all these games are online either so stuff with a small punish window (e.g. dash attack -> jabs) is gruesomely difficult to fit a hit or throw into thanks to lovely things like input lag and the like
I think it's harder to hit, but you can definitely do it.