Thank you. Through much practice, I've managed to consistently beat Marths as Roy, and the same can be said for practically any matchup except for Mewtwo and Spacies, but the Mewtwo I played against was number 1 in my state, so I won't think much of that, so, thank you for this comment!
However, I struggle a lot with Spacies as shine just leads into so much often regardless of DI, and I know you can chain grab then 0 to death, but that's only on FD or FoD when platforms are down, and it still requires you to grab them which is tricky as they have persistent hitboxes into shine then they jump away before I'm able to react. If I try to CC, aerial approaching with d-air , n-air, shine, or some combination of aerial into shine makes me combo food.
I have learned about SDI which gives me approximately a snowballs chance in hell against them, but I was wondering if they had an underlying weakness I could exploit in neutral. I know their recovery is lackluster, but starting combos to lead me into an edgeguarding scenario is giving me trouble.