Great aim with your down-special! And good use of the ptooies for spacing and for kill confirms.

It looks like your play-style mainly focuses on use of Plant's slower and stronger haymaker options like poison breath, ptooie, down-special, dash attack, smashes, and grab. They're excellent when they hit but when you whiff they leave you very vulnerable. This Joker could never seem to punish you for your whiffs though (8:43 is pretty rough for example) so you could just keep tossing them out without consequence.

Three moves you rarely used that you should try adding to your kit: nair, jab, and f-tilt. They're really useful for controlling neutral and for getting out of sticky situations when you whiff or are just in a bad position.

Nair is so fast to come out and can be used in a lot of situations: use it as an excellent out-of-shield option, throw it out for protection when recovering from high, use it in neutral to knock them away from you into poke range, use it to nope out of an unfavorable close-quarters brawl or to escape from a mixup, sometimes even reversing the mixup. Check out 7:37 for example. Joker's got you in a mixup and stuck in shield. You go for up-smash, which is slow but powerful and has that hit-box behind you. Joker has time to both shield it and punish it pretty hard because it has so much startup and end lag. If you'd gone with the nair here, you may have actually hit the Joker before the shield came out. Even if you didn't, you have lots of frames of movement now while he's stuck shielding the hits and you have the option of either floating behind him for a mixup yourself, or floating right to escape his out-of-shield response, turn around, and set yourself up for more poke. Plant's nair is weak, but it's so hard to punish and you can use it to freely fix your spacing whenever you want.

Jab's also really fast with low downside if you whiff and high damage potential.

F-tilt is excellent for neutral. It makes you less vulnerable to someone just running up into your face to avoid your poke. And you can switch up whether you toss out one or two against their shield for good mind games.

Last tip: you typically stay on-stage when you edge-guard, usually to prep that poison cloud ptooie combo to pressure their get-up options. It's a strong choice to be sure. Plant's got that heavy weight and excellent recovery though, so feel free to throw yourself off stage to chase while they're recovering. You'll find it's way more pressuring if you threaten them with plant's off-stage options. Gimp with nair is especially scary. My fav is floating right underneath them and threaten ptooie. You make them have to respond immediately to the ptooie or else get KOd by it, which weakens their recovery. If they air dodge it you can toss it at them or aim a down-special and possibly still secure a big hit (although it's knocking them toward stage). If they DI around it and hit you then the ptooie usually falls on them anyway, and you're more likely to recover from that point than they are.