The team to clear them quick is always built the same, but everyone's final 2 Pokemon are different
Make sure Whimsicott and Torkoal are below Lv.30, just to be sure they get OKHO'd from opponents.
https://pokepast.es/22bf5f1956494237
Whimsicott will lead with Torkoal, as soon as Torkoal brings the sun out its done. Whimsi will go first with Prankster to use Tailwind. If for any reason it lives to see a 2nd turn, memento something on the other team, killing itself and leaving the pain of -2 Atk and Sp.Atk on whatever you pick.
My final 2 are Nidoking and Flygon. You cannot use Typhlosions for Fire gyms (Flannery, Blaine, Chilli) and these can be used and sweep sucessfully without Tailwind and Sun
They can be used in electric gyms but I'd stick to Typhlosion since HP-Ice is attracted to Electric types in this game, and can be a pain for Flygon and Nidoking.
Sometimes I only use 1 Choice Specs and have the other using Charcoal. Just in case you need flexability and you might need a Solarbeam.
In Juan's Gym (Hoenn #8) his Kingdra is Lv.90 and will survive 2 full HP choice spec eruptions (x2 modest 31IV 252EV)