Rex - B2 - Kylo - Boba - Shore viable?

Could you link your swgoh.gg page. Without it people can't give specific advice. Based on what you've said, you should aim for Rex lead, kylo, nihilus (3* is more than good enough even at end game), shore or baze if you have him, and either chirrut, boba or B2. Without gk, you can't build the perfect Rex squad, but this will definitely do the job and secure top 20 depending on your mods, maybe even top 5. It will be able to take down zaul.