Alright, I think I got dthrow stuff worked out.
It seems best to dash pivot after high percents, rather than rar a jump or do a standing turnaround. I was testing and people need to react to the dash pivot just as much as the rar.
There's no 50/50s, but rather you just keep the opponent in a bad spot even if you guess wrong.
If they DI in to disallow bair, uair > Dair/SJP confirms easily. Kills from as early as 80% to whenever since once they're too high for sjp to connect, uair itself will start killing.
If they jump in, uair/dair/sjp cover similar options though I'd just go for uair unless you bait an airdodge. With no jump, uair sets up for a great landing trap.
If they jump away, bair/fludd is great. Generally I charge fludd while facing away from them and cancel into usmash/bair when they get too close. FH B-reverse fireball if they go low and try to edgeguard from there. (Falling fludd after fireball is pretty good)
And if they airdodge the bair, you can still land nair (or bair if they go too fair). It also tends to hit them inward, i.e into the stage. Setting up nicely for pivot usmash if they don't tech.
I didn't notice i could get nair because I forgot about airdodge landing lag.
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Lastly, still trying to grind out proper edgeguarding coverage. My mentality is to cover as many options as possible, for as long as possible, as safely as possible (i.e without using a jump), since if you get hit out of it, you'll die. Also, if you use a jump that means waiting a bit before sjping otherwise you won't snap, and jump frames add extra time too.
The best looking flowchart seems to stem from FH Fireball to cover the ledge grab while you get in position.
FH Fireball > SJP (to grab the ledge or punish jumps)
This seems best when you know there's no time to really edgeguard. If fireball hits, it can true combo into the stage spike sjp while you grab the ledge. If it misses and they still grab you get a trump chance or maybe even stage spike with the ledge grab hitbox.
In my experience, it's best to ledge jump instead of going for the raw trump against a lot of chars. Bair isn't very strong and doesn't actually confirm from a trump on a lot of characters.
Ledge jump lets you pressure buffered options as well as a potential regrab still.
FH Fireball > Cape In > Uair > SJP
This lets you cover the ledge grab with 4 hitboxes very quickly. You can also hold in after the cape to grab the ledge if they went past you or deeper. Uair DOES STAGE SPIKE when you hit with it like this.
Can also bair/fair if they airdodged while you caped.
This seems optimal for edgeguarding recoveries you have to try getting the 2-frame of. Like sheik, sonic, luigi, etc.
FH Fireball > Cape out > Bair/Cape in > SJP
Same as above, but a fair bit harder since you need to b-reverse AND angle SJP up to make it back without a jump.
*Note: Cape out > Uair doesn't work, you can't make it back without a jump. Bair pushes mario in a bit which is why he can make it back.
This seems best to challenge recoveries that can't be challenged head on. Like Marth, Luigi, and Mario himself.
The cape out will cover a high recovery, the bair a slightly later one, and sjp a very late one.
I was also looking into optimal coverage while holding the ledge. Since it's lower, these don't really apply.
The main options I found were:
Cape > Cape > SJP
Ledge drop uair > SJP
Ledge drop bair > SJP
(For bair, make sure to space it inward to cover 2-frame and angle sjp up so you can make it back with no jump after)
Not sure which is best usually yet. I like double cape since it's easiest and lets you react to stuff better. Can also sjp right after the first if your timing is off, you won't snap if you do it right away but it's often untechable when done like this. Not incredibly punishable if you're reacting to their recovery, too.
If you delay the cape a bit, you will snap though. But then it's only one hitbox so idk.
Overall, I'm starting to think of cape as a half jump when edgeguarding. I think just throwing it out might be the best way to start most edgeguards.