Only requirements for playing a gig is that your up to the gig itself.
It's a lot different playing in a packed stadium, in a local bar or at a kegger.
Pretty obvious statement, but many of the replies here have made certain assumptions about what kind of gig Energy might have been thinking of.
Truth is there are even some players who know nothing about theory and yet can fill the dance floor with one note.
To know your instrument inside and out would seem like the ideal, but you only need to march to your own drummer, and assuming you can do so in a manner others find enjoyable, you will be gig ready.
Play for the song, in sync with the band and the audience will enjoy themselves.
Then once you're gigging, continue your progress by honestly assessing your strengths/weaknesses against the backdrop of your desired progress.