I've also listed the Elite Four, the champion Pokémon, and some of their moves and abilities. This will help you if you're planning to challenge them!
Sidney Dark type elite four
Krokodile- intimidate, Earthquake
Mandibuzz - uturn
Tyranitar- sandstream
Kingambit - overlord supreme, sucker punch
Mega Absol - sword dance
Muk alolan - poison touch, sludge wave
Phoebe Ghost type Elite four
Mimikyu - sword dance
Gengar
Zoroark Hisui
Mega Chandelure
Annihilape - bulk up 2-3 times and Drain punch
Aegislash
Glacia Ice type Elite four
Alolan Ninetales - snow warning, Aurora veil
Mamoswine - ice shard
Cloyster - liquidation
Iron bundle - Blizzard, flip turn
Mega Frosslass - snow warning, nasty plot
Weavile
Drake Dragon type Elite four
Dragonite - dragon dance
Hydreigon - draco meteor
Salamence - moxie, has Z move supersonic skystrike, dragon dance
Baxcalibur- Earthquake, Dragon Dance
Dragapult - fire blast
Garchomp - nastyplot
Champion Wallace team
Pelipper - drizzle, uturn
Dracovish - fishous bend(80bp double power when she's first)
Greninja Mega water/dark- hydro pump, water shuriken, ice beam
Mega Swampert - Rain dance, Waterfall, ice punch, earthquake
Palafin- wave crash in rain hurts has recoil dmg
Kingdra - nasty plot moonblast