You seem to have a defensive Yoshi, which is fine. But whenever your opponent forced you to go offensive you left a lot of openings. See, defensive Yoshis like the ground, where they can CC, not get their jump gimped, fsmash space, and start a few combos with utilt and ftilt. But when you went offensive, all the Fox had to do was jump around. Luckily, that particular Fox didn't quite know what he had to do to punish you, but a better Fox would have jumped on each of those missed aerials with a drillshine to something else. I think you need to improve your offensive game more. With that defensive Bowser, you got punished quite a bit from attacking his shield. Now I know the Fortress is fast and all, but he can't hit you with it if you don't blatantly attack his shield. Especially with dair, its hard to l-cancel through the shield. Try some more offensive grabs, neutral-b, and empty SHFFLs, to get around the shield problem. Also, work on tech-chasing. That comes with time, though.
Oh yeah, stop using back roll so much. Its like your panic button, and I started predicting it a third pf the way through the match. I don't really know what a defensive Yoshi is supposed to do, though, since I play rather offensive.