If you could define your terms for us? Is JATC a training position? When you say Platoon, are you referring to a Fire Company?
Other that, the process for dealing with a training problem is the same everywhere. Develop a standard. Train to the standard and if you have people that for what ever reason aren't making the cut off, conduct what ever remedial training is required to get them to the standard. Whether it's physical fitness, understanding the written material or skills drills. If after counseling the person, getting their side of it and telling them what they need to do to progress, continue to give them individual training to get them up to speed. Repeat these steps as you dial the person in. If you continue to have the same problems (if the person continues to perform in an unsafe manner or can't perform physically) start separation paperwork. Maintain a record of all counsel sessions and remedial training plans and how your troop has responded to both.
Let us know if this is what you meant and how it progresses.