Azumarill is a great sand counter. Choice band is not even necessary if you keep it to counter sand team specifically.
Sing makes azumaril soo dangerous. Especially if you have wish support. In fact, I only recommend using it if has wish support. With 240 hp evs, 52 atk evs, and 216 defense evs with an impish nature, this thing has 401 hp, 298 atk and 275 defense. Bring azu in with wish support to ensure 100% health. Sing, belly drum. With those evs, azumarill will ALWAYS survive a jolly outrage from garchomp, which is your worst case scenario.. Granted, the sand will often kill it afterwards, but that is only the worst case scenario. Otherwise? Have fun sweeping. If azu gets low, just send in the wish support again, and rinse and repeat.
I don't know how effective it is against hail though :/. Also, it kind of expects wish support + rapid spin support, but then again, that's you have a team right?