Today, however, it could be
When I cast it, we can forget about all the other plot twists (the card is in exile, I can cast it for free, I must cast it at sorcery speed, etc.) and the only thing that matters is that I'm indeed casting it
As far as strategy goes it is very important to move Darkrai from your hand to your bench when you need the have a possibility of the defending Pokemon not attacking, also I would definitely play Dark Slumber right away to make the defending Pokemon asleep and then use Dark Resolve especially if the defending Pokemon is asleep and it should be because of Dark Slumber
No, Stifle cant target turning the disguised creature face-up, as this isnt an activated ability or triggered ability
Please note that there can be a premium to pay at these types of specialty stores like Card Kingdom though