Shady Fox
You could've won. So close. Basically, your biggest problems in my opinion were missing techs. He punished you hard a number of times for that. Just work on never missing them in combos. You also gotta stop doing the same thing from the ledge every time. Ledgehop wavedash is great, but you can beat it out if you know it's coming, and that seemed to happen a lot. Sometimes simply ledge hoping a jab, rolling or jumping are better options. Just try to mix it up more.
Shady Marth
So against marth, once you have him in the air, NEVER let him down. He just can't beat out well placed uairs. And you can easily get up on platforms for tech chases more often after you've started to combo. On the defensive side, crouch cancel marths more often, just like against sheik. Marths always fall for that until the higher levels. Oh and grab more. You didn't grab much that game at all. And the final thing I noticed was that when you were recovering, you could've stopped his edgeguards several times with a rising uair. It works super well, but be careful because sometimes opponents can bait it and punish with a kill.
And I don't know enough about doubles to help you there so I'll let others comment on that.