The cornerstone of function is the gait cycle. Movement occurs off one leg onto the other. Movement in sport and in life in general for that matter require the body to reduce and produce force in multiple planes in a myriad of permutations of the gait cycle. The commonalities are that movement is off one foot onto the other in one-foot landings and takeoffs based on the interplay of triple flexion and triple extension.
The training implications should be quite obvious. Train on one leg, train off and on one leg, and train both legs. The proportion of which is determined by the demands of the sport and individual needs. The single leg squat both from a standing and seated position is the foundational exercise. That is the remedial movement. The lunge done in all three planes is the centerpiece. The step-up done on a lower box with alternating legs and high box with single leg is another essential movement. Finally the double leg squat, although less functional is another general strength exercise. Start with bodyweight at one rep per second rate of execution and progress from there.
The single leg and reciprocal leg movements with appropriate resistance will bullet proof the athlete and build a great foundation for sprinting, landing, planting and cutting that is done off one leg onto the other.