I would recommend not 3 exercises but 5. These are called the big Five. They are: Squats, Deadlift, Bench Press, Press, and Rowing. The protocol you use to do these exercises is up to you (but I recommend deadlifting at the most only once a week).
It is fine to do exercises such as bench press without a spotter if you know what you are doing. I bench press without a spotter and I do fine. It is safer to have a spotter but not necessary.
Push-ups, bench press, military press, and push press
a concentric muscle action.
There are many good bodybuilding exercises...For mass there are squats, bench press, pull ups, bent over rows, and deadlifts are all staples. There are also a plethora of other exercises for all muscle groups but you will gain the most mass off of those.
Chest
Close grip bench is probably the best triceps exercise on the planet. This exercise allows you to go heavy and put maximum stress on the one muscle besides the pecs that can help increase your bench. You want to set up like a regular bench press, but position your hands no wider than shoulder width. On the descent, you want to keep your elbows in; do not let your elbows drift away from your body like you would with a regular bench press. At the bottom of the movement, you want the bar to come to the lower portion of your chest; at the top of the movement, the bar should be over your upper chest
if you mean bench press, then that is deltoids, triceps, and pectorals (or chest)
this is more than two but the best exercises for building strength and size are bench press squats dead lift and military press
a 14 year old boy shouldn't workout too much as his muscles are still forming and growing. Exercises that will help to enlarge the pecks are barbell bench press, incline barbell bench press, decline barbell bench press, and decline dumbbell bench press.
Bryan loves to workout. His favorite exercises include the bench press and the neck press. He is currently a junior body builder.
The bench press is a compound exercise that builds several muscle groups. Bench press works primarily to build the chest (pectoralis major) but also builds the anterior deltoids, serratus anterior, coracobrachialis, and the triceps.