Are we limited to only cosplaying a cosplay from the theme?
Of course not!
Honestly I doubt most people ever even know there is a theme. Some people definitely do choose cosplay that match the theme, but more often then not the theme just boils down to what the art assets on badges and other con stuff will have.
Cosplay whatever you want
(IN COMPLIANCE WITH CITY, STATE, AND FEDERAL LAW AND CONVENTION RULES AND REGULATIONS)