What you wear to train depends on the class you attend -- here are three basic setups outlined. As you progress in your training you will find what best suits you & your comfort:
BJJ Gi - this one is obvious for training BJJ Gi class. Rounders MMA offers gis for sale at the front desk, but you can also find options online. Make sure it is clean before class.
BJJ No Gi / Wrestling / MMA / Muy Thai - Compression or fitted shorts/leggings, and rash guard (or fitted t-shirt with sleeves). Long hair should be secured in a ponytail or braid.
*Please be mindful of your training partners by wearing clothes that do not have zippers, metal, or other buttons; try to keep nails trimmed.
For Muy Thai you will also need shin pads, training gloves, and a mouth guard.
For Boxing you will need boxing gloves and hand wraps - headgear and mouth guard are required when sparring.