I'm using this team for gyms at the moment:
Torkoal: I used wide lens for a while so that heat wave wouldn't miss but I ended up selling it because torkoal rarely gets to attack. I use charcoal now because it's cheaper and will power up the rare heat waves.
protect (I only use it when I know eruption will not one shot a special attacking pokemon, like slowking for example)
I use mild, 252 hp, 252 sp att but torkoal's nature, ivs and evs are not that relevant because it rarely attacks, it's usually only targetted by special moves and its main purpose is setting up the sun (and the rocks, although not as important).
Typhlosion: choice specs
eruption (only one that matters, I maxed out the PP so I can do 2 gyms without healing)
cut (to acess celadon and vermilion gyms if you don't have the ocarinas)
timid, 252 sp att, 252 speed
I also tried modest + choice scarf but I think it's much worse: specs can 1 shot almost every pokémon that resists fire, scarf cannot, plus typhlosion is rarely outsped even without scarf.
Aerodactly: wide lens (for rock slide to never miss)
fly (fly between gyms)
adamant, 252 att, 252 speed
It outspeeds everything anyway, so I use adamant for extra power.
Krookodile: life orb (soft sand can be used too, but I like the extra power of life orb, despite it forcing healing in between gyms more often)
earthquake (can be used against air baloon holders, because aerodactly will always break the baloon first with rock slide)
rock slide (for flying types or levitate)
jolly, 252 att, 252 speed
You don't need extra attack because of moxie.
For most gyms I use torkoal + typhlosion: 1st turn, eruption and stealth rock. stealth rock will stop those annoying sturdy or focus sash holders, but aerodactly can do the same job with rock slide if torkoal faints before setting them up.
Some gyms are easier with aerodactly + krookodile (the rock and fire ones): just spam rock slide + earthquake (krookodile will be last so moxie will activate).
Note 1: sometimes the first pokemon have sashes and that's quite annoying because they can attack typhlosion and make it useless/make it faint. When that happens, I just let it faint or change for krookodile, spam earthquake and when torkoal faints, change in aerodactyl.
Note 2: torkoal + typhlosion is imperative against the water gyms because of the rain.