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Says on Serebii you get given the GS Ball in Goldenrod after beating The Elite Four at the communication center, but that's only for the Japan version. Unless they also put the communication center in the US and EU versions, they probably just give it to you in the Pokemon Center.
He evolves at Blush Mountain now. Crabrawler can also evolve earlier as they give you access to the first area of Mount Lanakila where you battled Gladion in SM.
Sweet, Lurantis gets Superpower. Now it can abuse Contrary much better.
I've seen some people say Lycanroc gets Stomping Tantrum too. It's boosted by Tough Claws.