[@TheIrishJJ] Okay, so here's who I've thought of so far:

In place of Ally Sheedy, you could use India Eisley. She has the look and even has a sort of weird look that you were looking for in Ally.

In place of the nerd, perhaps another Victorious alum, Matt Bennett(known for playing Robbie). He's plenty nerd-esque if you ask me. Alternatively, Daniel Radcliffe or Asa Butterfield could apply here.

And in place of Matthew Brodrick (the cool/jock type), that's a wide open pool. My top choices for this role would be KJ Kapa(is known for his role on Riverdale as Archie Andrews), Dave Franco (younger brother of James Franco), and if you're not opposed to a different ethnicity, Chinese actor, Ludi Lin could apply here, too.