So far she's very neutral oriented. B2, F2 and f3 are her main tools here.
B3 has crazy range but it's jump bait.
Her dashes are slow but her walkspeed is solid. Bark skin cancels chip and reduces damage heavily so try to have it on as much as possible.
In juggles f21 xx bark skin is safe and you can meaty b1 after. I didn't test this against all wakeups so not 100% sure about this yet.
She has a few plus moves that I can recall atm. S3, 213, b3p and 1212, I'll check if there's more but those are the ones I remember.
Drills are slow but they have their uses, bark skin + drills is great for counter zoning. With trait out it becomes actual zoning.
Don't use them in halfscreen range or closer otherwise you'll get punished.
Grab is a shitty wakeup but it helps against 50/50s that lack range like Canary's or Beetle's. At least it's reward is big so it's worth the risk of trying it every now and then.
Trait is the deal breaker for her, it recharges really quick so having it out as much as possible bumps Ivy from average to wtf status. The burrow is like +11 and it launches for a combo, but she's stuck in animation for it (Like Quan's bat bite).
She has mixups but they're not unreactable 50/50s, however with trait out she can basically go nuts with pukes covering her, you need to learn the timings like the combo above to be in sync with Ivysaur.
Her throw in the corner can be "looped" SFV style, they're right besides you and the timing of her coming down from the flower pillar makes it hard to tell when she can attack.
Also random note, Ivysaur's puke stuffs a stupid amount of wakeups. Getting a knockdown with trait out means that you'll get free oki coz doing a wake-up is suicide.