In order to take a +2 Adamant Balloon Earthquake, it has to invest in a hell of a lot of bulk (practically Max/Max and a boosting nature). Even then, it can still die with Stealth Rock up.I'm pretty sure Azumarrill is a straight counter to Excadrill. Azumarrill has the bulk to take an Earthquake.
Plus, Azumarill should always use Max Attack and Adamant nature. It's simply not worth it to use Azumarill if you don't. But it can't take the hit by doing that. Azumarill shouldn't be trying to counter Excadrill. It should stick to OHKOing it with Aqua Jet.
I agree that if Sand Veil Chomp is found too haxy for voters' comfort (or if he's actually, y'know, broken), then we definitely ban Garchomp, not Sand Veil Garchomp. Even the "it's uncompetitive" people couldn't make an argument for banning Sand Veil Garchomp, because they'd be dealing with a single Pokemon, not the whole thing which is "uncompetitive" (Geez, I hate that word).