The main things to watch out for in Zard's neutral game are nair and jab. Jab is extremely good at covering every option except non commitment. Try to dashdance and get him to throw out a jab, dodge it, and then slip in with a fair, nair, or even grab. If he's doing nairs facing away from you, wait till the initial hitbox goes by, then full jump in with a fair, but watch out for the lat hitbox, the backswing. That's why you're full jumping. Once you get a confirm, Zard is pretty much combo food. He can recover fairly well, so try to combo him into an actual kill instead of having to edgeguard him. He should be easy to uair juggle, and once he's at very high damage or it seems like he might be able to escape the juggle soon, sweetspot a bair, which should be easy because he's huge. To edgeguard, probably just stick to fair for the most part. As far as recovering, just try to sweetspot. I'm not sure if his nair backswing will hit you out through your blazer, but it's probably his best option. Be careful of him trying to edgehog you. If it seems like that's his preference, start up Bing higher to land on the stage. You're probably still screwed, but it beats definitely being screwed.
I'm no expert but I do play both of these characters and I'd put it at 60:40 Roy's favor.