As these leotards are used for activities with a lot of movement the leotard either covers the shoulders or has a strap to prevent wardrobe accidents. A strapless-like appearance may be achieved through the use of skin tone or see-through fabrics though.
For ballet and dance practices it is frequent that these leotards are worn with tights and typically feature flat colors. For gymnastics it is most common that they're worn barelegged and it is not unusual for them to be made of a material featuring a sheen to them.
Official Gymnastic competitions have modesty rules for the appearance of the leotards worn by competitors. While these do not bar someone from competing, violating it will immediately result in point deductions from their score. The main restrictions on leotards are:
May not be made of transparent material
The neckline may be no lower than the sternum and the back may be no lower than the shoulder blades
May not feature narrow straps
The cut of the leotard at the top of the legs must not go beyond the fold of the crotch
