knee jerk responses: you overuse dair, downb, and sideb. you acknowledged the overuse of specials, so there's that. get used to only using them as punishes or out of conditioning people. also, be careful of using aerial downb when in range of the stage. you did some risky ones that could've easily gotten you hit back offstage before you got your dj back (and i think there were a few where you did get hit before you got the dj back). don't dair too much unless it's a good punish. you were using dair oos a lot (especially game1) and it's sloooooow. like, you're not getting a hitbox out until almost frame30 slow. it has its places, but you were missing a lot of opportunities to go for better options like nair or uair oos (or maybe your preferred spotdodge-jab/grab : p).
you also criminally underused float, but you're coming from smash4 (right?) so there's that. use it to mix up when you're coming in with an attack or to just hold up in the air a little bit to assess the situation before you decide whether or not to dj back and bail out. also, for going much deeper on edgeguards (or just hovering over the ledge to wait out stall options easier). when recovering, if possible, use dj-wizkick-hover-dj-upb. you almost always want that dj when you hover on recovery, otherwise it's very easy to lose more height than is feasible when getting back to the stage.
in general, use more nair in the neutral, as it's super safe. you used fair a bit too much, but you used it with good enough spacing to not just outright get punished, but use more nair unless you're aiming to get a punish. also more sh-uairs. best example i could find is 4m32s where if you'd gone for uair instead of fair, it would've hit and he would've been offstage. you also underuse bair : p i guess you actually kinda overuse fair overall : p get used to mixing up with sh-rar bairs and sh uairs. bair might not be as useful against ike (not entirely sure how well it works out in the matchup, tbh...), but uair is definitely still good, along with nair.
for ike specifically: there's a "safe zone" for qd, where he'll be in jump squat if he tries to do stuff out of it. right around 2m50s is a good example of that. you could've walked forward and basically jabbed on reaction to his release and hit him (or tried to predict and gone for d/ftilt) and he wouldn't be able to get you with anything out of it.
when he aethers, you can typically catch him with uair or d/ftilts (depending on his height), you just need to learn the spacing and timing for it. you were letting ike get back on stage a lot more than you should have because you weren't used to doing this.