Decided to think over this chart I made before and try to come up with better replacements for DR characters.  
I replaced all schoolchildren except for the CMC, since they alone kinda fit into the story. Now, let me go over the exact changes I made.
 
Hajime Hinata — Stygian  
Honestly, why didn’t I think of that before? He fits perfectly! His “pony of shadow” form is essentially Izuru Kamukura.
 
Chiaki Nanami — Gabby  
Cute, helpful, a bit cloud-headed.
 
Sonia Nevermind — Silverstream  
No changes here, it’s a good fit.
 
Akane Owari — Yona  
Same as well.
 
Hiyoko Saionji — Scootaloo  
Now, Hiyoko, Ibuki and Mahiru all have a history together, that’s why the CMC will work best with this trio. Scoots is Hiyoko, since she was shown to be a capable dancer.
 
Gundham Tanaka — Gallus  
As before.
 
Kazuichi Soda — Star Tracker  
Geek, probably a technophile too.
 
Mahiru Koizumi — Apple Bloom  
Another part of the trio.
 
Teruteru Hanamura — Pistachio  
Country boy with big dreams of a big city and a big career! Thanks for this new character, “Best Gift Ever”!
 
Nagito Komaeda — Sandbar  
Nothing to change here, the best fit of them all!
 
Nekomaru Nidai — Iron Will  
I did not want to include any, uh, old characters, but I’ll let this one. They have too much in common: loud, trainers, huge and bulky.
 
Ibuki Mioda — Sweetie Belle  
Remains even with the changes mentioned before.
 
Peko Pekoyama — Smolder  
Since Fuyuhiko is now Spike (more on that below), Smolder fits here quite well.
 
Mikan Tsumiki — Marble Pie  
Shy and possibly a yandere.
 
Fuyuhiko Kuzuryu — Spike  
Smlolder’s young master and a heir to the Dragon throne! Probably. Wants to be tough but looks cute as a baby.
 
The Ultimate Impostor — Ocellus  
Stays the same, but without Tiara as an exterior.