The thing with Excadrill is you need him to Revenge kill threats like Thundurus and Volcarona if you keep sandstorm up, and you need a second water resist due to drizzle teams. I found Rachi the most replaceable member for Latios, but you can replace someone else if you find rachi THAT useful. I have mentioned bronzong because he laughs at your two sweepers. They can't even touch him. You're not fully weak to him. I feel your team does well against other sand teams but it really gets screwed by Drizzle teams. Take my suggestions, they really fix the team weakness.
