I think it’s mainly for the big attacks like Lycanroc’s GX attack.It’s a shame Donphan already has 130 hp meaning a riotous beating would leave it with 10 hp anyways. Still, interesting card.
Also to anyone who says that Donphan isn’t that good, a reminder that you can use Last Chance Potion for the turns that Hustle Belt can’t hit OHKO range.