Bolster Warrior (Midrange variant) is pretty decently strong to bring to a tournament format.
Everyone is going to be bringing Dragon/Tempo Warrior, Zoolock, Aggro Shaman and Token Druid.
Bolster Warrior does well against Zoolock and Aggro Shaman. Does ok against the aggressive Warrior decks too because the taunts block chargers and weapons though Defend the King is far less good.
I don't know how the match up is against Token Druid (I don't imagine it being that bad to be honest, Bolster + Defend the King is hard for Druids to deal with and the big taunts are hard for Druids to remove anyway) but you can ban that out if you wish.
You lose to control decks though. Cthun Warrior, Renolocks, Nzoth Paladins etc. Probably one of the worst decks against control simply because you don't put up enough early game pressure on those decks and by the time you start presenting threats they out value you and clear your stuff easily. But again... this meta is good to Bolster Warrior.
I am not sure what a refined list would look like though. I kinda like one King's Defender in there. Sparring Partners are hilariously bad cards, occasionally I have gotten utility out of them but I feel there are probably better 2 drops to run, maybe Armorsmiths if you are going the full anti aggro route. Senjin also feels weak in it as the 4 slot, I feel like I would rather have Evil Heckler for the offensive taunt. Of course I got Tauren Warriors in there but you need an extra 4 drop in there. Experimented with the new Annoyotrons and Sunwalkers, the Annoyotrons have been alright. Bog Creepers do work generally. I finish it off with Rag and Varian, Varian being exceptional because you are likely to set up a huge taunt wall. I don't have Soggoth but I would imagine that it might make the cut.
I am also starting to think a copy of Brawl would not be bad in this deck despite it being a heavy minion oriented deck. Decent combo with Defend the King because it increases your chances of clearing all of your opponent's minions.
There is also the other Bolster variant which is far slower and control oriented that also incorporates armor gain. That might even be better anti aggro.
Edit: Saw an older Bolster list with Dread Corsairs. That might be interesting but that card has always been sketchy for me.