You could throw out an ftilt to challenge a grounded attack, or a nair to challenge aerial ones.
Usmash at the ledge is great.
Charging Flare Blade at the ledge is great, too.
Jab to Usmash psuedo-combos at 90-110 maybe even higher.
Fthrow (off the ledge) at mid percents can set up dair spike pretty nicely. And if you succeed or fail the first time next time just pretend you're jumping offstage, and then hope they recover above the ledge so you can smack them with a rogue fsmash or something.
Offstage fair is pretty good, even the sourspot. Bair if they try recovering over the ledge. Bair stage-spike or side-b to fair/upb stagespike if they recover low (like fox, pit, marth, etc.). You can also run offfstage and counter predictable recovers.
Throw out a dash attack on landings, like after you throw someone, or feign a juggle attempt (empty hop fastfalls and such).
Utilt kills, too, but there's not really a set-up for that.
In general, you don't wanna throw out fsmash at kill percent just because past 90% all the tilts and some of the aerials are liable to kill anyway. Save fsmash for 60-80% jank near the ledge. You can set it up as a tech chase I guess, like if you dtilt or jab, then chase and surprise them with an fsmash.
That's all I got so far.