Congrats for Leader's Choice of the month. Btw considering you can't hold any item, does this mean that Acrobatics will always have 110 base power?
Yes. Also goodbye Knock Off!
I was drawn to this metagame because it's a lot like taking the current generation and sending it back to Gen 1 without all the wonky mechanics and physical/special split, among other changes. Team building comes down to the Mons, nothing fancy, pure and simple.
I expect Talonflame to still be viable here, because as Chopin has noted Acrobatics deals 110 damage, and while it misses out on the power delivered by a Choice Band, its targets will be weaker without any HP and/or Defense investment. Sure, Talonflame won't be able to invest in Attack either, but nabbing a Swords Dance shouldn't be too hard when you come in on a Flying-weak target. Its high Speed stat and the lack of enemy Choice Scarfs should relieve the effects of losing Gale Wings as well.
Overall I see stall taking a harder hit than offense with the loss of Leftovers, Eviolite, and most importantly the inability to invest in defensive EVs. Before, a defensive Pokemon had the benefit of stacking HP with either Defense or Special Defense (or both), whereas offensive Pokemon can only increase their power via one investment. In essence, this waters down walls more than it does the Pokemon they used to check. To add insult to injury, walls aren't hitting back any harder now because offensive Pokemon tended to invest in Speed + an attack stat, so the lack of EV investment in that scenario is the same.
With Levitating nonsense out the window, plan on seeing more Ground+coverage Pokemon. Garchomp has solid natural bulk, an okay Speed, and a high Attack. Will it continue a hazard lead role or might it shift toward Swords Dance? What about fellow Dragon Salamence? Intimidate is gone, but with the threat of Choice Scarf Latios gone as well, if it grabs a Dragon Dance it can rest assured nothing will be able to revenge it until Mamoswine comes packing Ice Shard (another Ground+coverage user.)