Good job with implementing upB into your game, you're now upBing as you should and getting great reward off of it, as I am sure you noticed. Honestly, overall your aerial game is really good, definitely top notch lots of the time, but what you're lacking is a good ground and neutral game. I mean sometimes I see really clever things like you empty jumping underneath your opponent waiting for a reaction, or jumping above him, which are top level things to do (seriously this kind of stuff is what separates the good from the top), but you could use some more patient play, cause usually you're just attacking. You're also waiting when you should attack... Like when DK is above you on a platform just nair, you don't need to bait anything out because his shield is so bad you'll poke it 9.9/10 times.
So what do I mean by ground game? Dtilt, jab and grab. As for grabs I counted like 2 ATTEMPTS TOTAL between the 2 sets, one of which was a failed tech chase from the previous grab. I know it's hard for gaw to get grabs, but they are so crucial to land, you have to find a way, and funnily enough jab and dtilt can help you so much. Dtilt is ESPECIALLY crucial vs pika, because pika has such quick aerials he can really contest you in your comfort zone (uair to nair was getting you a lot as you know), so sometimes it's a good idea to stay grounded, empty hop or SH aerials and follow up with dtilts. If Pika thinks he can just run up to you and RaR uair, you need to show him that dtilt will be there ready to stuff him... And a lot of the time dtilt will be DI'd in such a way that they will be knocked onto the ground and you can read a get up with a grab, or w.e you feel is appropriate. Jab can be used to interrupt things and then can link to grab (this is not a true combo) if they don't react fast enough (this happens a lot, believe me). Other than that in regards to pika you did really good, and lots of the problems came from him just reading you/out playing you.
With DK, it was funny to watch because it was like you played perfectly stock 1 (game1), got unlucky, kept it together and won. Then game2 it was still a really good match, and game3 you kind of **** the bed. The reason for this is because you're approaching the same way most of the time... You need to approach with nair a lot in this match-up, and it has to be space properly. If you nair a little early so only the last few hits at the very tip of the hitboxes, you can harass his shield safely, and it usually only takes one on his shield to bring it low enough for the next one to poke. Also vs DK on BF, dair when he;s below the lower platforms is a godsend, because it pokes him, however don't do it too much for DK can counter it with utilt. And if you do hit with the dair, I usually follow up with a buffered platform drop into fair. I also do this if I hit shield (this applies to all characters you can poke through the platform). If you use this tactic on shield it's actually incredibly safe, even vs snake, so don't be afraid to do it (note it should be a retreating fair).
One other crucial thing is your ledge get-ups, as in you never mix it up. You're always trying to do a ledge hop aerial, and atilla read you a couple of times and got easy dsmashes on you that he shouldn't be getting. Don't be afraid to ledge hop air dodge past him, or normal get-up, or get-up attack, or anything. All options are readable, and all options can be a mix-up, so just because some options are traditionally viewed as poor doesn't mean they can't work.
EDIT: I want to add on edgeguarding DK. It's tricky as GaW cause you don't want to stale your fair, yet that's really the only move that solidly puts him where you want him. Well actually this isn't true, there is another option, and that's upB. What you do is you position yourself below and away from DK , and then upB diagonally into him which will send him very little up, and a lot back. Sometimes this will kill straight up, but most often he;s just forced to upB again. So you drift back to the ledge, ledge drop and do it again.... and again... and again, for as long as you want. Actually if you do it right DK cannot recover, but the thing is eventually you'll mess up the timing and DK will get just enough more distance he'll make it back to the ledge before you can connect your upB. Also keep in mind that since upB stales, if it didn't kill the first time, it will not kill for the duration of the edgeguard, so you're gonna want to fair or dair at some point to finish him off. This is the best way to edgeguard DK as GaW.