Power of Nature, Space Distortion
"How about you uhm... Kurayami?"
"Call me Kurogami," Kurogami responded, cutting Shidou off as he was shifting the attention from him to Kurogami. Although it didn't end up the way he thought it would, he managed to redirect everyone's attention to him so he won't have to explain his superpower in a more detailed manner. After all, revealing one's superpower doesn't mean you'd have to reveal your trump card as well.
Midori was a different case, though, he just revealed everything about himself, which is essentially a good thing since that would open up more possibilities for him in supporting the entire team. It just goes to show how serious he was regarding the matter, so much so that he'd risk laying out all his cards just to win the tournament.