The ending felt a little abrupt. I was expecting a final confrontation with Orobas- even if they can't fight directly, there are other ways they can compete. As it stands, it feels his character arc just ended because the arc is over. They could learn that he was being controlled by that shady guy, and break him out of it. Then at the end, he could win, but after having seen the error of his ways, be the one to point out the value of the pot, netting him third place, like another commenter suggested.
Also, Iruma's arc was a little disappointing. The number of his friends who helped him out felt just a little too high. They had their reasons for helping him: friendship (Asmodeus/Clara), trade (Kerori/Kamui), and spite (Jazz/Allocer), but him having to get help from other people that often invalidates his victory a little. I guess his strength is that he trusts his friends, while most demons aren't so trusting (though they don't really act that way). Plus, Nafra really didn't need to reject a share of the points. He already paid back his favor to Iruma when he got him out of that hole. After that, he just wasted his time in the harvest festival helping Iruma. I also wish Lied got a bigger role. His confrontation with his genie should've been shown rather than told. His only real showoff moments involved bouncing his senses from person to person. Even if we're told that's impressive, it doesn't have the same impact as beating a boss monster or winning a series of games against a genie.
I'll just accept that this arc was more about touching on the accomplishments of the entire misfit class instead of any particular student.