Roy has good edge guard abilities. Big, swinging sword, and safe up special back to stage.
Work on B reversal. When you're in the air, you can hit B+direction, and your character will change the way they're facing. Takes practice to get the feel for the timing. So, say you drop down and throw out a f-air, you can then b-reverse to get facing the stage again and then up b back more safely.
Your down air spikes, but I think you'll need to work on the spacing to hit the sweet spot of the hit box.
Going off stage is risky business, and is pretty advanced stuff. Maybe work on your onstage pressure— catching their roll onto the stage. Having an up smash ready if they always jump up to the platform. Grabbing if they immediately shield after recovery.