Legal Question in Criminal Law in California

Yes, if she passes the Delaware bar exam. Graduates of any accredited American law school can take the bar exam in any state.

Your friend might also be admitted to practice in a particular case; this type of admission is called "pro hac vice," which is Latin for ""for this occasion." She would first have to be admitted to the bar in another state.

Sure, once if and when, the 'friend' successfully graduates from a properly accredited law school, and then passes the bar exam in the state[s] she chooses, and is officially admitted to that State Bar. Not before. To do so before would be the 'illegal practice of law', unless she seeks and obtains special permission from that state to appear in a single specific case in that state, usually under a sponsoring attorney from that state.