my main account currently owns 18 gyms, and my second owns 16. I have been doing it oldschool way, 2 phones, driving gym to gym. of all the gyms, easily 8 or 10 ofthem are level 10 gyms. and all of the gyms i control I am the final crown victor. every single one has a 2.5k+ snorlax in it. one has a 2800 but thats no difference really. one has a 2.7k lapras with breath/blizzard. and I changed it up for once and its holding well(probably because the prev 9 pokemon are a mix of exeggutor/vapor/snorlax/venusaur etc) which i put a 2.6k fang/flame blast arcanine in. and cp 2k+ arcanines may only have around 130-160hp, but that 100 damage is nutzo. I left a 2.5k vaporeon with hydro pump in one to test, and a bubble shot/hydro pump 2k poliwrath in the latest gym. when checking hp on vaporeons I noticed that whether it was 2.2k cp or 2.5k the HP did not go beyond 187 unless it was a 100iv or close to it, even then it was a 1-3 hp difference in a 200-300cp gap. so I no longer wasted any stardust on vapos except to get any last remaining one pure aesthetics to 2200+. all my snorlax and most of my pokemon are the same. lapras i have around a dozen each, almost all are blizzard, unfortunately one of my 100iv is a dragon pulse but i put it up to 2.7k none the less.
I was taking gyms with these 2 accounts long before the update, so I had tons of coin saved daily to buy inventory slots. both accounts are rocking 700-800 inventory. so each account is plentiful with over 150+ max potions, 100 max revives each, and between 70-100 200hp potions, 50 revives, and a lower number of other hp potions. one has 4 3.2k dragonites breath/claw, another has 8-9 dragonites between 2.9-3.2k breath/claw I use solely for attack, I never swap pokemon no matter what I face i plow thru with a dragonite because simply put they are just amazing. All my pokemon I drop in gyms have weird/stupid/funny names. ie some snorlax: ur.fat.kid, i.sit.on.gym, you.suck, shamoo, why.so.bad, ISIS, Kaboom, Allahu.Akbar, etc etc. so people have to stare at those pokemon CP and name daily.