I second the pressure weakness. Her camp game can only work if you don't have a fast or reliable projectile or don't have the speed to put a close-range pressure on her. Ever since the synth hitbox was replaced with a windbox, her best option is usually to nair under pressure or OoS. Plus she isn't great against CC...not terrible, but not great. It's hard to get in on her but once your're in, you're golden for the most part. Her standing grab has more range but more endlag, where her dash grab has less range and less endlag.; pivot grab seems to be a happy median of the two. Use that info to help you bait and punish her grab attempts accordingly. Her recovery is good, but rather predictable as far as guarding against it. Just don't approach from underneath her or you will probably get hit with a dair (or uair belly flop if they feel like it).
Finally I'd say her ledge game excels over many other characters. Easy as hell to edgehog with her, prime position for bair/dair edgeguarding, and she can get onto the stage rather safely for the most part (fair/nair or wd onto the stage). However if you see Ivy being too liberal with using the up-b on the ledge, just keep track of how many she uses at one time because she's only allowed 3 tethers before having to land on solid ground. After her third tether is gone, she's much less intimidating offstage. So she can stall, but she can get punished pretty hard for stalling too much....I hope my input helps a little.