For anyone curious, Sora and Yuri were Obelisk Blues (high ranking soldiers and special ops), Dennis was Ra Yellow (intel and espionage), and Celina was Slifer Red (basic units and grunts). I know this because I made it up.
The duel academy dorms don't exist in arc-v like they do in gx but they do exist and Celina is a Slipher Red, Dennis is a Ra Yellow, and Sora is an Obelisk Blue, NO further questions (<- would love to be asked further questions)