Well, my original (Sun) playthrough team was Primarina, Alolan Raichu, Lurantis, Salazzle, Alolan Ninetails and Kommo-o, so I had literally no defence until the final trial. Kommo-o was my defensive ‘mon, but that’s playthrough meta for you. My Moon team was Decidueye, Alolan Muk, Mudsdale, Araquanid, Alolan Marowak and Alolan Sandslash, all of which are slow, apart from Decidueye, who had a speed reducing nature because FML, so… you know. I will say this, I ADORED my Alolan Ninetails. She wasn’t my team MVP (that was Pancakes the Raichu), but she was my favourite member, and that’s in the team that has 5 of my top 10 favourite Gen 7 Pokemon in it.
As for there not being any Poison/ Ground types… maybe not in Alola, but I think Nidoking and Nidoqueen might want to have a word with you about that statement.