Here's how I did it in my only playthrough (talking about intense mode, I like my game as hard as it offers me)
Venam - 1 try; Vivillon with Psybeam was avaliable, she was much more interesting as Saki's tag partner
Keta - 1 try on both; Early Misdreavus makes this hella simple, in case it faints, you can always use your Bounce Palpitoad. If I did not have access to Misdreavus, this fight would be a whole lot different
Marianette - 3 tries; Had Infernape, I suppose any fighting type that can take a hit or outspeed will do. Her Cinccino is completely useless
Narcissa - more than 10, 20, 30... hell I don't know, she was mean; Tailwind Pidgeot and Mismagius did all the work in the end, would probably be much easier if I caught that pesky shadow Tangela. Very cool battle, Spiritomb AI could be more persistent about Hypnosis instead of switching it to Spite at random times.
Valerie - 1 try; Sawsbuck and Crobat bitch slapped her back to Akuwa Town. A well made battle though. Confuse Ray made Milotic hit itself 4 damn times
Crawii - 1 try; Hardest part about this guy was his puzzle
Angie - 4 tries; Lucky I had Magneton and Infernape when I got trapped, could have just as easily be wrong pokemon which would have made me start the game all over again. Well made battle, I liked it very much, maybe add Articuno to her team. Or is that going to happen later on?
Amber - 2 tries; First try Typhlosion solo nailed my entire team, second time Raichu got +4 and destroyed her. All of this could have been different if her Rotom did not decide to spam thunderbolts into my Raichu slot. This battle feels great though, probably because it's the first gym double battle.
Electric whatshisface - 1 try; Not much to say, it got a little tight in the end but I was prepaired for it since the info about his pokemon type is given to you way ahead of time. Maybe if he had a Mega pokemon and Zapdos. Otherwise I liked it, well made
Almost all of them were done without potions, I spent way too much on pokeballs. Keep in mind that since the beginning I was being sort of careful to swap around my pokemon to get them at least a little bit properly EV trained. After Narcissa destroyed me, I actually decided to EV train all the new pokemon I am going to use.
While I did not fail at gyms a lot, they are not by any means easy. Usually I had an answer to them, especially if the game gave me a little information as in what type am I facing. I believe moving Misdreavus somewhere later in the game would solve a lot, moving Emolga for example already made things harder.
Anyway those are some brief thoughts that nobody asked me about. Can't wait for V8 of my favorite fan game.