It’s all about knowing the angle of approach your opponent is using during a jump in, and using the best button that poison has for that. Don’t mind my shitty paint skills, but I tried to give you the sweet spots that her buttons are best for.
So for the standing MP, i like to use this for jump ins that come in up high, a good example would be a bison who is coming in with a head stomp or ex head stomp, Standing MP is a great option to swat it away.
Standing HK I like to use when the oppoonent is trying to jump to cover ground and get in but not necessarily jump in to attack. Hugo would be a good example. Or just at any range that the opponent is trying to jump in with near the tip of a jump in and i can take a little step back and kick them out the air.
Standing Mk i find works well against dive kicks that are coming in low or coming in from a neutral jump.
So pretty much why Crouching HP feels the best and much more consistent is because it itself covers a condensed version of all three of the previous anti air buttons. The Hurt box is also tucked nicely behind a big high hitbox on the last 2 frames which are the more common frames that end up being anti aired with. You can then buffer a HP Fireball which is relatively safe from most reversals and ultras and gives you added pressure.
Also consider that combining this with an onscreen HP Fireball which is at about the distance of the Green X in the Standing Poison Picture above when poison is recovered and can move again add’s to the pressure of getting an opponent to jump into one of those sweet spots. With good reaction and utilizing the quick fireball recovery she has, She does have great zoning potential.
I mean, just looking at all the angles she can cover at one time from one piece of real estate is pretty good, The only draw back she has is lack of active frames. a few more overall on her normals, and shaving a few off the recovery would really help. Most impotently though would be more active frames on her MK DP and with out any gaps between active frames, and being considered air born once the invincibility ends. By doing that, it wouldn’t feel like a grounded reversal tool, and a true anti air, which it looks like. Just to put it in perspective, the average active frames for a Dp style move is like 13, and poison’s MK DP has 4. On top of that, there is 3 frames (almost as much as the amount of active frames) of a gap between the active frames. so she has 2 active frames, 3 frames of no active frames which shes entirely vulnerable and considered grounded so she can be thrown or jumped in on and full comboed on instead of an air reset, or even sucked in from a tanden engine, then the last 2 active frames with bigger hit boxes, one on each side of her surprisingly, and then it goes into an air born state and recovery.
to sum it up:
Everyone elses DP usually goes like this:
Invincible start up
First couple active frames which are invincible
remaining active frames while airborne
recovery
Poisons DP:
Invincible start up
First couple active frames which are invincible
few recovery frames which are grounded
remaining couple of active frames - still grounded
airborne state starts, active frames ends
recovery