I had an Emolga go through the Sky Trainers because, hey, Electric is good against the Flying types. That Aerodactyl smashed it down. Only Sky Battle I lost, too.You know what was an annoying NPC battler? That one Sky Trainer that had an Aerodactyl! You probably play through the game with maybe only one or two flying types. Since this is before the end of the game, it probably only has STAB attacks. I legit only had one flying type: a Pidgeot. Despite being overleveled it could just not break through it before being KO'd. When I played through X I had a Salamence and I remembered to get my revenge on her (him? I can't remember)
I had similar difficulty. I had an Emboar, Krookidile, and Galvantula as viable attackers. Haxorus pretty much swept. I used a ton of Revival Herbs, Hyper Potions and the sort to stall out and ensure that my Emboar hit enough times to KO with Head Smash. It took me 30 minutes lol.OK, I'll share an experience.
BW2 Iris was absolutely insane for me. My team was Serperior, Darmanitan, Swoobat, Terrakion, Zoroark, and Azumarill I think? I don't remember but it was something like that. Hydreigon went down from Terrakion, same with Druddigon and Aggron. Lapras was destroyed by Serperior. Then Haxorus comes out, survives Darmanitan's Superpower, and sets up a Dragon Dance. It proceeds to sweep my whole team with Dragon Claw, X-Scissor, and Earthquake.
But it doesn't end there. I end up catching a Zweilous, evolving it into Hydreigon, replacing Swoobat, and trying again. Haxorus again, sweeps me after a Dragon Dance. Then, I challenge her again, and finally beat her Haxorus. Then Archeops comes out and kills Hydreigon with
Brick BreakDragon Claw or something like that, then sweeps my whole team with Acrobatics, Earthquake, and Rock Slide.
I finally beat her due to some luck with the Quick Claw, allowing me to actually beat her and enter the hall of fame. My Hydreigon was something like level 74 by then, so I ended up completing the afterstory with pretty much just Hydreigon.