Movements in the gym must transfer to everyday tasks in order to be considered functional. There is no point in training in a manner or style that is not useful to what you actually do on a daily basis.
Deadlift - The king of full body integrated movements, for strengthening the posterior chain. As simple in theory, as picking a weight up and placing it back down. An action we as humans, perform every single day. Load, repetitions and frequency are all person/goal specific. Each variation initiated through the hips are assistive in building hip strength, advanced lifting techniques and posterior stability. Do them. Often.
Plank/FLR - Core stability is a challenge in this movement. As with anything, proper form is the priority. The correct musculature must be forced to stabilize the body in order to keep the benefit. Scapular stability, in conjunction with upper body muscular endurance, are also largely beneficial through this movement.
Goblet Squat - One of few strength movements that address mobility. The resistance is held chest level, through out the transition, from standing to squat and back up. This will stimulate a neutral spine as the anterior load is the catalyst for posterior activation. Weight position also builds strength in the abdominal and quadricep areas.
Turkish Get Up/TGU - A full body integration movement that readily promotes stability, coordination and balance through multi directional stabilization movements. It can be rehabilitative and preventative at a manageable load, step by step, ground to standing and back. Heavier load may be used to build strength.
Farmer’s Carry - The single most transferable thing you can do in a gym. You pick a weight up (or two), stabilize yourself and take a walk. That simple. Once described as a “moving plank”, it is another core stabilizer. In addition to grip and leg strength, the entire posterior chain is strengthened with every step. Scapular stability and rotator cuff activation are added bonuses.