Squad Arrangement

Hello, I wanna build a squad for arena battles, but don't know which character should I use? I've got Luminara, Sidious, Vader, Phasma, Hk-47 (droid one), Talia, Ima-Gun Di, Ahsoka, Mace, Fives, IG-86 and Chewbacca and lately using first five of them. If you have better combo for squad, please tell me. Thanks a lot already.