It's not that hard to hunt a HA, just sos call at least 30 times,get trevenant with harvest skill swap and trick, use skill swap to change the pokemon's ability to the pokemon that used skill swap then use trick to give it your leppa berry then get a pokemon with false swipe, I would max out it's attack because alola sandshrew gets iron defense that sharply raises it's defense, then sos call at least 30 sandshrew, Then use skill swap on the 30th sos called sanshrew to see if it has slush rush, if not keep repeating each time it sos calls a sandshrew until it has slush rush, then get your leppa berry back with trick, then knock it out then proceed to catch the ha sandshrew. I suggest getting T wave pokemon or one with spore, when a pokemon has a status condition, it cannot call for help. So that's your chance to catch it. it seems complicated when I explain, but it's easier to just do it and you'll learn as you go. Who knows, you might even get a shiny trying to hunt down it's HA :) Happy hunting
