I've finished two playthroughs using Primarina/Vikavolt/Salamence/Mudsdale/Salazzle/Pangoro and Decidueye/Magnezone/Crobat/Arcanine/Starmie/Bewear.
Primarina: S tier. Brilliant movepool (Scald, Sparkling Aria, Moonblast), great stats, great typing and early availability.
Vikavolt: Up to C tier...