Sup McBuckets
First to tell you, nice job in finding 3 players with near the same height and they can all get some training in the same spots. Newer players often have trouble figuring this out as many want to go a OKC Thunder or TWolve/Sixer approach to basketball and try to develop many positions. (Even I tried to do that when I started) Thing is BB has a weird training program and we must do it their way in order for ourselves to improve
Now, on to the good stuff. I would say the 6'5'' guy is the best because he has the best arrangement of skills across the build, so of course have him as one of your 2 main trainees. I'd also keep the 5'10'' dude as your other primary trainee because that passing is pretty nice to have already. Also the shorter the player, the faster they will train on outside skills. While the 6'0'' guy is a MVP, I am not a fan of his Jump Range or his passing either (i think passing and handling are key to having a successful team in the lower leagues; lower AST/TO ratio means less mistakes which=more opportunity for PTS). You can keep him as a tag along or perhap sell for profit, because lots of guys will like to buy him just because of his MVP potential on his name.
I'd generally start off with either some 1v1 Guards to increase their jump shot, driving, handling ability and then go on to outside D to help them defend the perimeter better. I'd say a goal of 12 driving and 10 OD should be attainable by the end of the season and should be a good base start.
Good luck! If you have any more questions, you can hop on the discord here and shoot either myself or other managers questions you have about the game.
(https://discord.gg/qyEdS)3 Time NBBA Champion. Certified Trainer. Mentor. Have any questions? Feel free to shoot me a BB-Mail!