I find it really hard to beat Terra. I've been stuck in the same place for a while now. My Pokemon are:
Delphox: lvl 75
Ability: Magician
Item: Psychic Memory
Moves: Psyshock
Fire Pledge
Fire Blast
Psychic
Simipour: lvl 75
Ability: Torrent
Item: Sea Incense
Moves: Crunch
Surf
Brick Break
Acrobatics
Vulpix (Alolan) : lvl 71
Ability: Snow Cloak
Item: Quick Claw
Moves: Blizzard
Grudge
C