Flat, how experienced are they with training?
No real background other than chasing me around the gym on occasional Saturdays.
A lot of times all newbies need to train in a similar way just because they still need hypertrophy and their gains are going to be linear for awhile. Gaz's program has good exercise selection. I'd add maybe power cleans to that. For most exercises I would stick with 3 sets of 5 reps. You may want to go with 1 or 2 sets of deadlifts just because recovery is tough with deads. Cleans obviously need fewer reps - I'd recommend 1-3 per set. If the technique breaks down, you need to shorten the sets.
Will add cleans & limit deads. I'll have to learn cleans myself, as a PLer we don't do much in the way of cleans.
Just make sure they're moving correctly - get the proper flexibility and movement patterns down now and they will have a huge training advantage over others when they get older. You always hear about HS athletes who can "squat" 400 lbs., but then when you see them perform the squat, you realize that you are going to have to completely re-teach them the movement.
The main difference is going to be conditioning, a bit of exercise selection, and prehab.
Here's a good article on conditioning that I tend to agree with:
Heart Rate Training: Time to Enter the Zone
Good read
For the baseball player I would caution against doing a lot of overhead pressing movements and I would have him doing some shoulder prehab every week. Here's a good article on that:
Shoulder Prehab Program for Baseball Players | STACK Blog
