My team is:
Magnemite Rockruff Dartrix Growlithe Alolan Meowth (temporary) Eevee
Here are some suggestions
Hope this helped :)
Make sure your Magnemite has sturdy. If not, then replace it with a Magnemite that has sturdy. Teach it charge beam and level it up to about level 24. Then, it should be strong enough to overpower the totem Araquanid. A sturdy Magnezone will be a great help later in the game, so this is a worthwhile investment.
Or...
Level Dartrix up till it learns a flying move Go back to Melemele and enter ten Carat Hill Get Flyinium Z (guide online) Go back to the trial Lead with Dartrix and bust out Supersonic Skystrike on the first turn.