I'd like to share some thoughts about what I found strong/what I found myself building with:
A Pokemon I found myself using every team I made was Weavile

, using this set:

Weavile @ Choice Band
Ability: Technician
EVs: 252 Atk / 4 SpD / 252 Spe
Jolly Nature
- Pursuit
- Ice Shard
- Beat Up
- Low Kick
I mostly play BW OU as far as vanilla tiers go, and Latios is extremely dominant there, making Pursuit very good to have. When I saw that Latios wasn't banned in AAA, I knew Pursuit would be more important than ever. Weavile also provides Ice Shard support for other dangerous dragons, Thundurus-T/Zapdos, and Landorus-T/Gliscor. Both stay-in Pursuit and Ice Shard are boosted by Technician, both OHKOing Latios from full now, and better yet, individual Beat Up hits are boosted as well, meaning early in the game before anything goes down, Weavile has a near-automatic kill button to click. Steel resisting Dark still makes it less insane than it would be in later gens, but even reasonably bulky neutrals just get shredded by the full 6 hits of Beat Up. Low Kick is there for Steel types and the occasional Tyranitar.

An ability that anyone familiar with BW knows is extremely potent is Magic Guard, which not only makes anything hazard/weather immune, it also cancels recoil including from Life Orb. Anything can make good use of this ability, but the most tempting options would be Stealth Rock weak Pokemon that love the power boost from Life Orb: I brought

Salamence and

Tornadus. Betticus brought similarly potent options like

Thundurus and

Dragonite. There was even a

Staraptor from Pooshi, which benefits from not taking recoil at all.
Another option that I think I wasn't the only one who tried was

Blissey, who normally struggles with residual damage from hazards or status or weather, making it nearly unkillable without set-up.

A fun aspect of BW AAA was the ability to experiment with rain and sun setters better than Politoed or Ninetales. For Drizzle, I used

Slowbro while Betticus used

Slowking, and I theorized other bulky water options like

Milotic and

Jellicent. If something like a Band

Victini is a concern, then Water/Ground types like

Gastrodon could be an option for a guaranteed Victini Swap.
There's plenty of options for good Rain abusers, too: the genies

with Magic Guard or another good ability for them are obvious, but stuff like Hydration set up guys like Curse

Swampert can also be great. Shout-outs to Dry Skin

Excadrill for the guaranteed Latios switch-in.

For Sun, it gets more interesting. Taking inspiration from how good of a sun setter

Groudon is in Ubers, I tried Drought

Gliscor, for a bulky pivot that can set Stealth Rock and has reliable recovery. It's Scald-weak against rain is the main issue. The non-Scald weak option that would take inspiration from

Ninetales in OU would be defensive

Infernape, as insane as that sounds, given its access to Stealth Rock, U-turn, and Slack Off.
Sun abusers are also plentiful. The obvious ones are Banded Fire types like

Victini and

Infernape, with either Adaptability or Mold Breaker. Specs

Heatran is also an option. There's Calm Mind

Cresselia with either Poison Heal or Magic Guard in tandem with boosted Moonlights, and even something as simple as dragons with fire coverage like

Garchomp,

Salamence,

Dragonite, or

Hydreigon can be terrifying.

Conclusions:
Either way, I didn't get to play that many games because the first few rounds were all activity wins, but I was excited to try this out given my love for Gen 5 mechanics and how neat AAA can be and am happy to have won. The games I did play were very fun. GGs everyone.