What do teenagers wear to dance practice?

My teen(15, turning 16) is switching from gymnastics to competition dance in the upcoming season. A slight issue I did not previously think of is that she only wore gymnastics leotards to practice before but her new dance studio does not have a strict dress code for anything except ballet class. What exactly is typical dancewear for kids her age? When I searched it up I mostly saw little kids in like brightly colored matching sets but that seems to be more a younger kid thing. Should she just be wearing like shorts and a sports bra? Would it be inappropriate to wear a regular t-shirt to dance?