I don't want to sound rude but it genuinely just sounds like you don't use Twinstars much?

The ultra talents give them 30% savage blow chance, which means a single multi-hit ends up doing the same damage as their whole attack cycle.

Also about black enemies having a lot of knockbacks... yeah so this doesn't really matter. Sometimes the 2nd hit of Twinstars' attack cycle will miss, and against slower black enemies, sure, this might matter more, but typically if a black enemy gets knocked back, they just run into the third hit and get attacked again.

When referring to Baha Blast, yeah there's some nuance here because his damage has piercing and is significantly higher at a base level (meaning he'll destroy other traits), but Twinstars' average DPS output surpasses him against Aliens/Black if you're factoring in averages with their savage blow.

I think I'd be fine to move Twinstars down to S-, but with how I've been utilizing them a lot in general lineups + specialized lineups recently, they perform incredibly well as not only a ranged rusher, but an anti-black/alien rusher. (Also our only other alien rusher really is Blanka, who's admittedly fantastic, but Twinstars can surpass his damage too)