After the open challenge where few students from all the academies challenged each other to test the strength and skills of top competition without revealing too much of their own strength and skills, the tense atmosphere calmed down a little.
No one wanted to reveal too much of their skills by showing off in a battle just before the main tournament began. Not to mention the opponent could also refuse the challenge if he didn't feel like fighting.
Obviously Rio was very happy to comply with all the requests. Beating the crap out of dumbasses who thought it'd be wise to challenge him and see what he can do, was good for his health, after all.
As for spending his mana or showing his skills before the match up and all the other primitive stuff, it didn't bother him. He was confident he could beat all the students his class year easily after all.