So MUGEN's default juggle system is pretty much worthless. POTS left this behind to replace it.
Spoiler: POTS Juggle (click to see content)
Juggle "resets"
In fighting games, resetting a juggle means hitting an opponent out of the air with a move that makes him land on his feet, for example doing a weak Akuma hurricane kick in SF3 or SF4 and then using a normal attack on the falling opponent. Again this is something that doesn't happen in Mugen and can't be reproduced by normal means (Hitdef parameters), so to add this feature to your character you can follow this method:
1) For every attack that isn't supposed to make the opponent fall on his back, but rather land on his feet, give its Hitdefs an ID. I'll be using ID=200 here.
2) Add this code to State -2:
[State -2, P2 Recovery]; Notice how ID 200 is being used. ID must match those Hitdefs
type= targetstate
trigger1= numtarget(200)
trigger1= (target(200), stateno=5020) && (target(200), alive) && (target(200), hitfall); Hit out of the air while alive and already falling
ID= 200
value= 5025
ignorehitpause= 1
3) And create the corresponding State 5025 (or whatever you prefer) of course:
[Statedef 5025]
type= A
physics= N
movetype= H
velset= 0, 0
facep2= 1
[State 5025, HFS]; Resets the fall parameter, so that the opponent will not fall on his back
type= hitfallset
trigger1= 1
value= 0
[State 5025, End]; Sends opponent back to his own states
type= selfstate
trigger1= 1
value= ifelse(pos y, 5020, 5000)
Juggle "resets" - invulnerability
I wasn't quite sure whether this one should be mentioned, but well since there is one alternative to implementing this that is only one line of code (times N), it should be worth it. You can plain simply disregard this if your character allows opponents to air guard ground attacks and suffers corner push when hitting them in the air.
When you connect one of those hits that makes the opponent land on his feet, he should be invulnerable until that happens. Just fire up any SF or KOF game, hit a jumping opponent with a light punch and then try to hit him again as he falls.
There are several ways to implement this in Mugen, but the one most suited for a summarized tutorial consists of making every Hitdef only activate if the opponent isn't in hit states that make him land on his feet. Like so:
[State 200, Hit]
type= hitdef
trigger1= (p2stateno != [5020, 5040])
trigger1= animelem=3
...
Note: For special and super moves you may want to use just "p2stateno != 5040" instead. If your ground attacks are set up so that the opponent can guard them in the air then "(p2stateno != [154, 155])" should be added if needed.
It is also a good idea to set air.hittime parameters to a high value so that the opponent cannot hit you back either in these situations.
What are some other suggested methods? How different are they from game to game or is POTS's system fairly universal? Consider this a juggle master thread. I'm going to do some searches to find more juggle code options too.
More info and options.
http://mugenguild.com/forum/topics/checking-juggle-value-86690.0.html
http://mugenguild.com/forum/topics/the-juggle-points-they-do-nothing-91894.0.html
http://mugenguild.com/forum/topics/reporting-number-juggle-points-used-possible-not-possible-100146.0.html
http://mugenguild.com/forum/topics/juggle-point-problemsolved-more-or-less-122097.0.html