Battleship Squads (not to be confused with Battleship Squadrons) follow an older naval doctrine but are occasionally still deployed by many interstellar navies.
A BB (or Line) Squad consists of two Battleships of the same class and two lesser escorts (known informally as consorts), usually Cruisers or Frigates, and is under the command of a Senior Navarchos or a Commodore.
2-3 BB Squads were traditionally grouped together as a Line Squadron under the command of a Commodore or a Rear Admiral, with additional assets added as needed but, as has been mentioned, only the BB Squad remains of these “old school” formations. On occasion, a similar formation of two same-class cruisers (or even frigates) and two “lesser” escorts is assembled as a Naval Squad, but these are rare exceptions.
A similar concept, though different in execution and function, are the Commonwealth Royal Navy's "Hunt/Kill Groups", comprised of three identical battleships (most commonly Venatrixes), whose purpose is to decapitate TOG Battleship Squadrons by destroying the flagship.