They say all good things start with a strong foundation, well that is especially true with Dance Costumes. The correct foundation is essential for each and every dancer. One of my pet peeves at Dance competition or performance is dancers "flopping" across the stage in a costume without foundation or the correct supportive undergarments. Not only is this distracting but it is a source of potential injury for the dancer.
First let's talk about the ladies. Very young girls usually do not require extra support if their costume or leotard fits properly but please, no underpants under the leotards or costumes. Not wearing underpants is a different feeling that the dancers have to get used to but is the correct choice for dancers. As they grow they should wear a "G-string" or "Thong" for hygienic purposes. Each dancer's body is unique and so are their needs for foundation. As young girls start to develop they should be wearing correct foundations. Simply wearing tighter leotards that confine the body is not supporting or respecting the female form. Good foundations lift and allow shape, while giving support. Sports Bras may be all right for class but are not a flattering line on stage. The best thing you can do for a "well endowed" dancer is encourage them to go to good lingerie store for a proper bra fitting, many young women have no idea about their correct bra size. A well-fitted bra can be girl's best friend. When a dancer is wearing a bra under a costume it should not be visible, simply supportive. Many bras are available with clear straps or could be changed to clear straps. Should portions of the bra still be visible If tack the back of the bra to the costume. Also the best color is flesh tones, white or black will almost always show through. Many dancers like to wear a flesh colored "body-liner" under costumes, this may be more comfortable and allow them to change costumes more modestly. These liners are available from several different companies and all are quite similar, but as with the foundations they must fit properly. Wearing a liner that is too big will add wrinkles, bumps or odd bulges in some very odd and undesirable places.
Now let's take a look at the boys and men on stage. Every male dancer should be wearing a "dance belt". The belts come in a variety of styles and colors. Some are a pocket design, while others come in a full brief. The dancer should try different styles by different manufacturers to find the one that offers them the best support without restricting movement. No athlete would take the field without his "support" and the same should be true of dancers. A word to the teachers, it is up to you to inform the boys about the dance belts. In talking with other teachers and studio owners I have found that boys do not wear dance belts simply because no one has ever told them about the belts and how important it is to protect themselves from injury. If you are not comfortable talking to the boys try talking to their Moms, they in turn can explain it to the boys. Initially most of the fellows try to avoid wearing the dance belts because they are not the most comfortable things in the world, but like many things that are good for you, eventually they get used to it.
Dancers must take care of their feet. Do not wear shoes without some kind of sock or tights, bare feet in dance shoes is a easy way to get a fungal infection such as athletes foot. Always carefully dry the area between the toes after bathing, swimming or showering, the moisture is a breeding spot for germs. Not to contradict myself also keep the feet soft with moisturizers or creams. Shoes should fit correctly an allow room for the sock or tights but not be so large that they are loose on the foot. Do not hesitate to see your podiatrists if a foot problem such as an ingrown nail or bunion develops. Dancers feet take a lot of abuse, be sure to take of them and pamper them whenever the opportunity. Pedicure gift certificates are great gifts for dancers! A final issue while talking about everything that goes a under a costume or leotard good hygiene. Dancers must be diligent in keeping their dancewear and undergarments clean. If you are dancing and working in class then odds are that you are sweating, perspiring or as my grandmother would say "glowing", so please use your deodorant and keep all the clothes clean.
In conclusion I say, "support you local dancer" wherever and however necessary!