What should I wear bussing tables?

Something similar to what you noticed people wearing when you applied to the job.

Wear a full apron over your clothes so you won’t ruin them.
Underneath wear clean commfortable clothes unless there is a uniform you should wear.
Example of apron
And welcome to Fluther.

Does the job not have uniform requirements?

Some companies might have uniforms it depends on the location.

Isn’t it usually black slacks with a white button up or polo? Sometimes shirt color varies per business.

Usually this information has been given in the interview. But if you are busy all day comfortable shoes are a must. Seems to me there might be a no tennis shoe rule but that depends on the place, black is usually a safe bet.