This is my go to team. Never had a hard time with it and had overall easy time destroying everyone.
1: Blaziken (Adamant)(Blazikenite)
Blaziken is a beast with a huge multi type movepole to use but here is by far the best in my opinion.
A) Thunder punch (Water Weakness)
B) Earthquake (Great Stab)
C) Flamethrower/Blaze Kick (Stab)
D) Sky Uppercut/Brick Break (Stab)
Since Thunder Punch can only be learned post game so I suggest shadow claw to deal with his psychic weakness. All moves here have 100% accuracy and will counter more than half of all Pokemon types and still throw a hefty punch at the other types. If you utilize Pokemon moves with their types they do more damage but also using different types allows the Pokemon to deal more vital blows to other Pokemon types.
2: Gardevoir (Modest)(Gardevoirnite)
My favorite Pokemon and the best psychic Pokemon with the added fairy nature. You'll devastate almost everything with this movepole
A) Psychic (Stab)
B) Shadowball (Weakness/Other Psychic)
C) Moonblast/Dazzling Beam (Stab)
D) Focus Blast (Stab/Steel Weakness)
This is by far the best move set that will devastate anything thrown at her. Focus Blast has only 70 accuracy but oh my, when it hits and it being a fighting move utilizing her special attack, it hits hard.
3: Salamence (Neutral)(Salamencite)
How can I not include this beast of a Pokemon? Shame you can't get him early on but oh my is he worth it!
A) Fly (HM/Stab)
B) Steel wing (Fairy Weakness)
C) Dragon Claw (Dragon Weakness/Stab)
D) Flamethrower (Stab)
This is my preference for a very powerful move set and one I feel fits a dragon. Salamence has such a high attack and special attack he will one hit almost anything and destroy the highly favored Altaria by speed and attack alone. A good stand in till you get Salamence is Latias/Latios since you get them before you get the HM Fly and rather easily.
4: Gyarados (Neutral)
Another beast of a Pokemon that this time you can get early on. It's sight alone is intimidating to other players when facing them. Sharpedo is great and all but Gyarados is faster and has a higher attack than Sharpedo.
A) Ice Fang (Stab)
B) Earthquake (Electric Weakness)
C) Thunderbolt (Stab)
D) Surf (HM/Stab)
Gyarados has a higher physical attack but still a decent special attack therefore Ice Fang is stronger than Icebeam in that scenario but Ice Beam can still be used. With this move set Gyarados can crush all the other types without having to use a water hm slave for simply surfing. Waterfall is a good alternative though if you want to utilize Gyarados' higher attack.
5: Aggron (Jolly)(Sturdy)(Aggronite)
This guy is a walking tank simply put. Decent attack and op defense he can take almost anything. With this move set you will counter his biggest weakness (fighting type) and with his mega evolution looses his water weakness.
A) Rock Slide (Stab)
B) Earthquake (Great Stab/Steel Adv)
C) Aerial Ace (Fighting Weakness)
D) Heavy Slam (Great Stab)
Heavy Slam is his best move. Tailor made for Aggron as it does more damage the heavier the user and the guy weighs 800lbs! Aerial Ace counters his fighting type weakness and rock slide has a higher accuracy than stone edge so it's best to hit more as sometimes that's vital for Aggron
Now with the last one I wasn't really sure. These 5 can pretty much hold there on and together punch back anything thrown at them. So this is me personally, feel free to use a Manectric or Magnezone but this choice is faster and when it comes to battles, the first punch is the best.
6: Pikachu (Lax) (Lightball)
Now hear me out. I know Raichu is better. But I prefer Pikachu. Yes, Manectric and Magnezone are stronger but Pikachu is faster. She (mine is female) can hit first and when she does I make sure it's effective. Then there is the Light Ball that I found on route 119 (I think) that boosts her special attack and attack to rival Manectric and Magnezone. But again that's just my preference. With this move set Pikachu will dominate over her weaknesses and other electric Pokemon.
A) Grass Knott (Ground Weakness)
B) Dig (Stab against other Electric Types)
C) Brick Break (Great Stab)
D) Thunderbolt (Duh)
Grass Knott is perfect for Pikachu as it deals more damage the heavier the target and Pikachu is rather small. Dig deals with other electric types and brick break is just a good stab moves to deal with more difficult types like Steel. Thunderbolt is more accurate than Thunder and I'd rather be accurate.
This is my team. I've used said team in all generations (thunderbolt for Gardevoir for the older gens) and my team destroyed everyone. I never had a hard time and neither will you.
Now for HM slaves. You'll always need one till you face the Elite 4 and these are the three best, HM wise, to use:
1: Linoone (Pick Up)
When I learned this guy can pick up items during battle I immediately, on my next run through in Emerald, had four of them in my team as I trained Torchic and Ralts. Besides being fantastic HM slaves it's just nice to get pokeballs, potions, and even rare candies from them. Any who here's a good HM move set for Linoone to use.
A) Cut (HM)
B) Strength (HM)
C) Rock Smash (HM)
D) Surf (HM)
Wait Linoone can learn surf? That makes no sense. So can Aggron and that makes even less sense but zigzagoon canot be found right outside route 101.
For Water and you decided your water Pokemon should keep surf:
Wailmer is such a versatile HM slave. The Swiss Army knife of HM slaves as Wailmer can learn all except cut and fly.
B) Rock Smash
Now of course you can teach it surf but if you want your water Pokemon to use surf anyways without having to sacrifice other moves for HMs then Wailmer is for you. Relatively easy to get with the Good Rod he is the best for Water HMs.
Now let's say you don't want to use Latios/Latias as they are legendary and want to use a legit Pokemon to fly and don't want to use bird Pokemon. Then this one is perfect as it can use all other nonwater HMs:
Another versatile HM slave that can easily be caught before you get the HM Fly.
A) Fly (Duh)
B) Cut (HM)
C) Rock Smash (HM)
D) Strength (HM)
A great replacement for Linoone and stand in till your preferred flying Pokemon that are harder to get like Flygon and Salamence
And that does it for my best team for Alpha Sapphire and Omega Ruby. With the exception of Pikachu and the HM slaves they can all mega evolve. Only a few of their moves don't have 100% accuracy but still have quite the power. With the move set provided you can deal with all Pokemon types you'll encounter and just devastate anyone.