Actually, most states have restrictions against non-attorneys representing a business in court. (See for example for CA Merco Construction Engineers v. Municipal Court.)

Otherwise however a business can represent itself in court, so long as its representative is a practicing attorney. Many states (but not all) won't require the attorney to be licensed in the state of litigation so long as they are licensed elsewhere.

Also, all states will allow a business to represent itself in small claims courts, where attorneys are not allowed unless they happen to be an employee of the business.