Im only talking about treaty, I dont play supremacy.
For me, I play super agro with them. I win the first fight and push as close to their base as poss. Then I tepee up. I try to end the game asap because sioux is the strongest at the start as you can pretty much get all your cards before the treaty ends. Microing the pit is very important. When I have full pop, toggle damage, when need troops, toggle spawn speed, when the chief needs to kill artillery (use his area ability for them), toggle warchief hp also to res him obv. You dont have to do this if you can get hp treasures for him though, can normally just hit and run.
I make sure I have 10k wood when treaty ends and when I can spam infinite herds, I move more on gold. I tend to have ~25k Gold and Food when treaty ends which is respectable.
If im winning comfortably and have lots of res, I max out the pit. If not, I take some off.
I aim for war chief HP treasures, he is super important.
I usually just mass riflemen and have some rifle horses incase they try to use cav. Chief sits behind everything, he is basically an aura bot. I may send in axe horse if needed in small groups, if im sieging, use prowlers obv.
Tepee arrangement is just something you have to practise, best is to put them in a “U” shape. Make them waste their time on tepees instead of military buildings, you are only loosing 25 wood per tepee over way more from stables and barracks (like 200 or 300 per building, I cant remember), leave some gaps for your troops to move freely through them. Always max the amount of tepees you can build.
Also, they can build walls now which is awesome. Worth noting if you didnt know, walls are massively nerfed in DE which helps Sioux alot.
If you play them correctly and have as many auras from Tepees as you can get plus the chief aura plus firepit damage, nothing Ive found can stop them. They roll over anything.
Most of my games my KD ratio is around 1:3 or at least 1:2. The last game that I played before writing this, I had 400 troops in total and killed 1400 of the enemies. Sioux or Lakota is really really strong so far for me. Will be taking it to ranked soon.
This is my deck, I may change it. Playing around with it atm until I find something I like. Might put in some native mercs because I rarely need the wood crate card. The trickle card seems to be enough.
P.s I never use Tokala (dog soliders). I havnt found a use for them yet but its nice to know if I need a massive op army, I can get them with one click.