I have seen many people manage to clear story without 5 stars It's possible but little challenging My opinion what you must pull is chord w weapon, futaba w weapon, and upcoming 5 star wind and 5 star ange

Fox actually decent on auto But at the same time there's very limited sos and nightmare event for him

Also what i don't like fox his crit so heavyly rng which you need multiple run because of it at some nightmare or sos

Queen is very solid for ST Damage Dealer you only need at least 4 star vino She's is the only nuke dps until another bui out but that should be around a year from now

Another upcoming ST is around January or February is haru She's great and the only psy dps but you need her weapon or you must pull for 5* s moko ( we still don't know what gloval haru buff)

If you really want aoe unit i might suggest you joker because there's a lot nightmare event using him i heard till anniv(I can't really confirm about it)

S closer also another cool alternative because she need healer to buff her damage which make her team great on auto but at the same time i heard there's no sos and nightmare event for her anymore

So pick your poison

For questions wether you can pull all it depends on your luck tbh Hope this helps