Against Jaqui full auto, crouch and walk in to about mid screen, and hold crouch and react to what she does when you're there - you should be able to reaction block if she meter burns at the end (set it up in training mode and practice).
It's possible to sand grenade in between her bullet spam, and technically you win damage wise (9% vs 8% iirc), but frame data puts it in Jaqui's favour so you have to crouch and walk to mid screen instead. Anyways, once passed mid screen you play a reaction game:
* If she jumps forwards, she's getting anti aired/air to air. If you plan on D2ing her jump in, do be careful if she does her air stomp as this can cause your AA to whiff - delay your response slightly to see what she does (Erron's D2 is pretty fast anyway)
* If she jumps back, dash in and play the corner game
* If she bf2s, reaction block and punish.
* if she low rockets, you can just about reaction block.
If you have sufficient health and aren't too keen on being able to reaction block or just want to play it safe in general, then just go for neutral crouch block at this distance:
should she jump in, release block and D2 on reaction; if she jumps back to gain some space, she's only cornering herself; bf2 or low rockets you can block punish; if she does machine gun again you'll have to take the chip, but at this distance the pushback is a lot more manageable than say at full screen.
With Cassie, I'd say just zone her full screen with sand grenades/3,2 etc. She can't really do anything about it from that distance bar akimbo (which you can avoid by neutral ducking AND trade favourably with sand grenade), which forces her to attempt to get in making her a lot more predictable and more manageable to deal with. Up close, her strings are too fast to contend with imo; Play the MU at mid to full screen instead.
Scorpion I am trying to figure out myself, but so far it's very much Scorpion playing his game and you reacting to it. His teleports and minions let him control the neutral so zoning is out of the question and you've got to be on your guard the whole time as a result. When he's in hellfire variation, he basically gets a free breaker too
High meterless combo damage and his vortex really hurts - I end up saving/using meter just for combo breaking in this MU... but building meter safely to do that is proving difficult!