Vs Fox/Falco/Falcon
Pre~30, nair combos into grab, unless they buffer dodge. (If they do it once, they'll probably do it every time.) Nair g
Stomp at zero puts falcon into a crumple state, which you can combo into grab. Against the spacies, stomp knocks down unless it is decayed, in which case you get that same state. Stomp combos into grab after ~15, but it requires a near perfect l-cancel into running jc grab.
I'll mention that when landing stomp pre 40, the closer they are to zero, the more likely they are to miss the tech. No guarantees.
Below 40, you cannot combo stomp into grab or knee on reaction. You can, however, do it on prediction. After 40 it's more easily reacted to.
Side B might be the least advisable move falcon has, but it does put everyone into air knockdown at zero, assuming they aren't crouch canceling. It will auto combo into every aerial at zero. It does 7%, the same as dthrow, so while dthrow doesn't autocombo quite the same, the followup options are the same on hit confirmation.
Side b/dthrow (7) into knee (18) does 25%. This combo will knock down the spacies, and since it's at the lowest percent that the knee can knock down, it's another very commonly missed tech. While spacies must be at 7% for knee to knock down, falcon must be at 9%, meaning dthrow knee at zero leaves him standing. If launcher-knee leaves them below 25%, the knee can be comboed into grab.
At exactly 50, uthrow combos into dtilt vs spacies. This is also the lowest percent at which dtilt will knock down spacies, so it usually forces a missed tech. You've probably seen silentspectre do this. Interestingly enough, this combo starts earlier vs falcon, at 45%. You can then follow up into otg stomp, then knee.
Vs spacies, uthrow combos into uair around 65, nair around 70, and knee at exactly 100. vs falcon, the numbers are the same but about 10% lower.
Once they reach 40, combos follow the archetype of launcher-> extension / finisher, or extension -> extension/finisher, so on and so forth. You've seen IKM before, you know how it's done. While doing your 8 hit combo is all well and good, remember that people aren't ******** anymore and they figure out how to DI by the 3rd hit or so. Choose when you knee to optimise off the bad di; if they die from knee at 50, they're gonna start diing up a lot more.