I would train these two as PGs since they have horrible IS. The third you dont need to ship out, sure he is 19 and has starter potential, but that doesn't mean you cannot turn him into a viable backup option. Or even a cup game starter.
Since you should be making your two main trainees into PGs you will be training lots of OD and PA, so tagging the 19yo along with them will turn him into a decent backup. I would immeditely get started on OD up to 12 or 13. Then push PA to at least 10. After OD is at 13 and PA is at 10(for the superstar trainee), I would aim for a skillset like this for your superstar trainee:
13 9
13 10
10 10
Once the superstar trainee has hit that skillset I would re-evaluate and continue on from there.