I bred an Aerodactyl to use for the team I was given for the Elite Four (which i'll get to in a minute) and maxed out its EVs in Attack and Speed. I showed both screens with Super Training on the bottom for proof.
I caught my team members and started to do some training (after some EV'ing).
In training, I did Le Wow and had a perfect run (16 turns, 4-3-3-3-3 with no faints) and got 25 Balm Mushrooms for it.
I then got to the Elite Four. I put on the Set battle style and didn't use any healing items in battle.
Malva was pathetic, I used Hone Claws and then OHKO'ed her entire team with Rock Slide, even Torkoal as shown above. (Picture is super blurry but it was an OHKO)
Then we got to Drasna. A Sky Plate boosted Brave Bird from Braviary OHKO'ed her Dragalge, then it almost got Altaria but she lived and knocked me low with Dragon Pulse. Then when she healed, I brought in Froslass and OHKO'ed all three of her remaining ones, even Druddigon, with Never-Melt Ice boosted Ice Beam.
Siebold was no better than Malva. Mega Medicham OHKO'ed his entire team with Thunder Punch, except Barbaracle which I killed with a critical hit High Jump Kick (probably didn't need it even with Intimidate).
Wikstrom was a bit dicier, though. I got his Klefki down easily with Exploud's Flamethrower (2HKO and he wasted his healing items), and Aegislash I brought in Froslass to eat his Sacred Sword than did around half with Shadow Ball, then he killed me with Shadow Claw and Exploud finished him with Flamethrower. I missed with Focus Blast against Probopass first time, but I hit and then killed him on the next turn. Scizor killed me with Bullet Punch, but I had Hydreigon finish that off.
Lastly was the Champion, Diantha. Aerodactyl used Hone Claws against Hawlucha's Swords Dance and killed her with Fly. Tyrantrum survived an Iron Head and killed me with Head Smash, but then she died from recoil. Aurorus and Gourgeist were slammed by Exploud's Expert Belt boosted Focus Blast and Ice Beam respectively, and Goodra I 3HKO'ed with Boomburst then Shadow Ball then another Boomburst (she missed with Focus Blast first time and I got a crit last turn, not completely sure if I needed it). Gardevoir took just under half from Shadow Ball and killed me, then I had Braviary survive a Thunderbolt with 3/4 health (and get paralyzed) before killing her with Brave Bird for the win.
With that, I completed the Elite Four, making this my third time doing it on this game haha. I can provide team pics if needed.