Sensei! Bokutachi ga Sekai wo Horoboshimasu. - Vol. 5 Ch. 31 - Thirty-First Period: Fairy Visit

[Gletscher]

Naturally, class D can not be in the last place due to obvious reasons. We have hint that there will be a showdown with class S. However, I don't think this author is someone so shallow that would make class D somehow beating the strongest class with just a bit of trainings. They probably will lose unless Ibuki and Nagisa, the hidden trump cards, decide to go all out.

About the other class, I think it's fair that class D can beat class B, the fat jerk teacher's class. They all have potential and now motivation as well as respect for Solo sensei. Giving them training and they can grow much stronger. Maybe not enough to fully reach class B level given they are a lot behind, but Ibuki and Shao probably can cover the gap.

It doesn't seem to be a battle focused thing though, so maybe the other students might have something to show too, like delicious pastries and beautiful gardening... although it does give a sports festival vibe from the looks of it.
That said, my bet is class A gets first place (given what Solo says about them in the spoiler), class D gets second because they have plot armor, and class D gets last since Bib is not fit to be a teacher and is bringing his class down.