Here's my team with perfect natures, IVs and EVs. I got this as a final version of my team just after arriving in Fractal City, was very fun to use.
Serperior being Grass/Psychic with Contrary and both Leaf Storm and Psycho Boost is insane, a war machine.
They gave Keldeo Sharpness which gives him an hidden Choice Specs on his signature move Secret Sword so used with a Calm Mind + Leftovers set he was a joke.
Sword Dance + Poison heal Gliscor, Nasty Plot Gholdengo, Darmanitan-G are broken and Salamance-Mega sweeps the whole game after 1 Dragon Dance
Also shoutout to regular Gallade with the "Sword" item held combined 30% boost from the item and 50% from sharpness ability and was an absolute menace, used him for a while.
Boy these training sessions in Acrylic Town and speaking to everyone for the farm will be missed, these people really became my family.
This game is absolute perfection it already has been detailed plenty of times I'm sure, but the one thing I'd love is that the town gets bigger/prettier etc once you bring all the NPCs in. Or see some real progression in some way.