Julia=Pretty easy because her strongest mons is 5 levels below the cap
Florinia=Even though I use Fire starter (Torchic), that Breloom is so annoying if I can't OHKO it will spore and keep mach punching. After getting pidgeotto, it's easy tbh.
Corey=After caught Donphan near there and it's all good. Crobat took off my Blaziken though, but my Skuntank revenge killed it
Shelly=Even though she uses bug type, shes THE HARDEST for me. 2 raindancers, BUNCH OF BUBBLEBEAMS, I trained Emolga and stealthrock graveler to beat her up until level cap from morning to night, and it's still a close call.
Kiki=My Emolga solos all her mons with Acrobatics except for Lucario who gets killed by Donphan's EQ
Aya: 2nd Hardest. My poor Donphan is less useful due to EQ being halved. Trained Steelix which isn't that useful when I used it alone in the end due to her mons mostly special attackers, and a local Muk with Minimize and screech. After her Dragalge fainted and her battling mons are Drapion and Toxapex, my steelix and muk succeed in setting up and it swept the rest of her mons with Gyro Ball.
Noel=My Blaziken solos after some potions and setting up with Bulk up. Super easy.
Serra=Same with Noel, except that I don't use potions but luck instead on not missing any of the blaze kick and HJK
Radomus=3rd Hardest I suppose, but it's 2nd longest because around this time is where I began to catch mons to form a solid team. After my settings completed, I defeated him pretty easy with Omastar and Dustox after setting up.
Luna=Easiest, all I need is 1 Paralyze Heal and Blaziken swept her entire team. No switching, no potions, no setting up. Her Bisharp is too weak.
Samson=My Emolga solos. Needs Scolipede set ups for that Hawlucha though, but no potions. Very easy.
Charlotte=Catching 2 Prankster Cottonee that helped me alot with setting ups, and after set ups, Omastar and Blaziken swept all her mons easy.
Terra=has some problems with Swagsire due to its unaware. But leveling up until near the level cap and harassing the swagsire by switching back to setters works well.
Ciel=My Omastar solos after set ups. Super easy.
Adrienn=after training my setters because it's so underlevelled (from 20 below xyr weakest mons to about 7), my Medicham and Omastar defeated them. My cottonee isn't work here so it's a bit harder.
Titania=I went to her Gym without team preparation and using 3 HM slaves Orz. No PC to heal or switch to gym team is what makes me spent so much potions for Blaziken to bulk up til max while enduring A-sandslash EQ. That excadrill ohko with critted EQ 3 times in my playthrough idk why, but I win in my 4th.
Amaria=that Rotom-W and speed halving field makes it so hard to setup stuffs and that Wishiwashi is just monster. Switched choice to Double Battles and it's really easier I win in just 2 tries (partially due to the Vaporeon changed the terrain to underwater which helped my Omastar to sweep so much in my 2nd tries)
Fiore Mansion tag battle=Solaris took 2 of my revives and about 4 hyper potions but that's it. What makes this hard is that because it's a tag battle and your teammates have little knowledge in setting up stuffs, Flo is the best out of all of them (the reason I purposefully losing against Solaris on 1st fight) so it helps a little bit. Also Flo is rather useless vs Blake