MvC 2: Air grabbing

How exactly do you perform air-grabs either to punish a mistake or end air combos? Every time I try doing this P or HP ends up coming out instead.

You have to make sure they’re not in hit stun/block stun and you press Forward or Back with P or K when you’re in throw range.

I’m not quite sure why you would want to punish a mistake with an air throw though.