The fight lasted for another minute or so until Simon got a sneak attack in on Shiroi. As someone who's experienced in powerful area of effect attacks and big flashy moves, Shiroi can't go head to head with someone proficient at close combat range. That's why every time Simon sneaked up on her, she would be backed into a corner and forced to waste her energy on powerful ice moves. It didn't take long before she got cornered with no choice but to forfeit.
On the other hand, Fuuka stood a chance against Satoshi had she played her cards right. In the end, she couldn't beat him as well since he could somehow anticipate her next attack. No matter how much she tried to hide her presence, or lessen her movements so Satoshi wouldn't sense her invisible attacks, nothing worked on him. It's as if he had eyes everywhere, ultimately forcing Fuuka to waste her energy until she was too exhausted to go on.