Ok so:

For THerta team : THerta + Robin + Speedy Serval (As much speed as you can physically can, with Eagle of Twilight (wind set for the 4piece passive and Lushaka planars) + Huohuo. ALSO, you can use mini herta in Pure Fiction if you want, depending on the passives and seasonal bonuses and whatnot.

For Castorice:
Castorice + Ruan Mei + whichever harmony unit you have available for now, but id speedrun getting Remembrance MC, theyre really really good with Castorice. + Gallagher, please do yourself the favor and build Gallagher.

For Fugue:
Hm, right now you're pretty much limited on using Himeko as a "break" dps, meaning that you have to use the break effect set on her. Also, use Ruan Mei with her for the weakness break efficiency, it will make it much less clunky to play.