Finally hit top 50 in fleet arena, and I've been using the full Sith fleet. Starting lineup of Vader's TIE, B-28 Extinction Bomber, and Sith Fighter. Depending on the enemy fleet, I'll interchange Hound's Tooth with B-28 and call it in as first reinforcement.
Other reinforcements are Emperor's Shuttle, Darth Maul, and Boba (usually never gets called unless the battle goes super long).
It's surprising how strong the B-28 can be even at just 5* and the Sith Fighter/Concussion Mines go right through the Protection on Hound's Tooth.
Is anyone else running the Sith fleet with any success? I definitely don't see any Sith Fighters or B-28's in the top 50 on either of my accounts