UNSC Everest

The UNSC Everest is a Colony ship and also servers as the 3rd fleets flag ship

Armaments 

• Presumably at least one Magnetic Accelerator Cannon
• Point-defense guns

Its branches are
Marines
O.D.S.T Orbital Drop Shock Troopers
Spartan Twos 

The ship works with the others and holds most of the officers in the fleet