Here are 6 intermediate to advanced level exercises that can be done anywhere, anytime as they require nothing more than your bodyweight and a wall. Below is a very extensive video tutorial for all of the exercises.
Exercise #1 - Feet Elevated RKC Plank With Opposite Shoulder Touches - Develops lumbo-pelvic stability, shoulder and scapular stability, and to some extent, upper body strength
Exercise #2 - Feet Elevated Long Lever Triceps Push-Ups - Develops lumbo-pelvic stability, shoulder and scapular controlled mobility, and upper body strength (triceps)
Exercise #3 - Feet Elevated RKC Side Plank - Develops lumbo-pelvic stability, and shoulder and scapular stability.
Exercise #4 - Single Leg Glute Bridge With Foot Up Wall - Develops posterior chain strength
Exercise #5 - Feet Elevated Forearms To Hands RKC Plank - Develops lumbo-pelvic stability, shoulder and scapular controlled mobility, and upper body strength
Exercise #6 - Rear Foot Elevated (On Wall) Split Squats - Develops lower body strength, most notably, in the glutes and quads.
All of these exercises can be made easier by keeping your feet on the ground, and not elevating them on a wall.
With all of these exercises, it’s extremely important that you own 100% of the movements, and are physically and mentally present the entire time.