Clutterfunky

I might actually pick up those exp mods myself, since grinding is one of the big things that gets me burned out in this game. 

I actually just tanked through Aya; Prankster Reflect+Gastrodon+a few more poison resists meant I could just tank hits from Toxapex while it helped to whittle down Aya's other, more offensive mons. It even finished off Dragalge for me! It was the last mon left, so my own last mon (Ampharos) could just beat it straight up. It took a few tries, but once I stopped wasting time setting light screen (Merciless means that 'Pex's Sludge Wave ignores screens) it was fairly simple. But, once again, heavy type advantage, and as a more defensive gym, I was really in my element lmao.

I actually had much more trouble with Fern, due to my multiple ground and dark weaknesses, his Krookodile was a massive threat, especially if it rolled Moxie, and with Camerupt as my fire type I didn't really have as clean an answer to his grass types as I would have liked. I ended up training two different dark types partly because I hated how vulnerable I was to SD+Sucker Punch Decidueye.

Remember how Fern supposedly trounced Shelly despite the bulk of his team being at a severe disadvantage from the outset? I'm all but certain that she went easy on him... albeit out of the anxiety he likely caused her, if we're being honest there. On the other hand, I haven't the slightest idea as to how he got past Aya with supposed ease...

Speaking of Aya, there is a significant difference between her fight and the other two you mentioned: her's is a Double Battle. It's more than a bit difficult to balance a team to be effective in both Singles and Doubles, and since the latter is so uncommon, it naturally winds up getting the shaft most of the time. It's a bit more difficult to run a bunch a glass cannons when they can only deal with half of the things looking to take advantage of their frailty, ya know?

Thanks to the pokemon not going over the level cap during the battle with Fern I one shot most of his pokemon except decidueye and that was only because it had a faster attack stat than my Talonflame and knocked it out, but that was the only pokemon he knocked out of my party. 

Fern is the type of person who just needs a real, good, solid punch in the throat- something I'd gladly give him after my own verbal thrashing, lmao