Her weight especially. If you can abuse the follow ups that a lot of characters have on her, do it.
Also most of her attacks can be crouch cancelled. Like a stupid amount of them. Try to crouch cancel just about everything.
Her grab. It's awful. It's possible to react fast enough and grab her out of it with characters like Ike and Marth. It's pretty large, but it's crazy slow. Should be a free punish on a whiff.
Her recocery. Tether punishing is this "weird concept" where you hold the ledge, and just hit her as she waits all 80 freaking frames to get back on stage or offstage (she can go either of the 2 directions). However, make sure to have invicibility frames here because you will be hit off by a fair, razor leaf, or even a dair (if they are stylish). Make sure to keep regrabbing ledge to refresh invicibility.