In terms of practical danger of releasing block at a bad time during run jabs in effort to counter, this is a list of the logical damages that can be done from characters in a common scenarios, but I will throw in some tactical options here and there for characters who do not have reasonable rub jab damage potential. Remember many pop up combos start with knee lifts so you can attempt relaunchers with whoever has them but I will keep references to them to a minimum. This list is not about which characters have the tightest RJs or best corner advantages.
I will try and do juggle LP options tomorrow, the list will probably look a little bit different than this. Corners as well, unless someone else wants to review that info, and then we can cross reference all the lists and come up with something to determine RJ values for all characters.
Reptile - damage is quite variable from 43-100% depending upon opponent - vs Shang Reptile can do 3 hit pop up to forceball, aaHPHP, Elbow Dash, aaHP, Elbow Dash, Uppercut for 43%, vs all other characters Reptile should be able to score a minimum of 50% and infinite up to 8 characters I believe. There are more but far too difficult.
Stryker - damage is quite variable from 40-100% depending on corner placement and opponent. Stryker can RJ (for chip) Robot Ninjas, Sheeva, Kung Lao, Kabal, Shang Tsung, Jax, and Kano. Throwing out a kara jab with Stryker can bait attacks easily, so always go for a cross screen or corner inf variation (if available). Vs Shang his max mid screen combo is 4 hit pop up, Riot Gun, Baton Dash, aaHP, JK for 40%. Overall his RJs are the least effective pound for pound but his damage is high on characters he can use them against.
Human Smoke - 50-59% - H Smoke's standard B&B combo of HK, LP, JK, TP, Spear, 3 hit pop up, aaHP, JK, air throw works on every character except Sheeva (substitute JP and it will work with a few % less) and it does 56%, the problem is when you are RJing, you tend to overlap the last 1/3 of the screen so connecting the JK to TP can be tough on some characters, so you might want to stick in a TP - aaHP after, reducing damage a bit (vs Shang mostly), or, if you are close to the wall, leave out the TP and go with a corner combo to break 60% in most cases. Remember it's not always about completing a repetitious combo, but utilizing the most with what you have. Also remember H Smoke can relaunch everyone. Specifically vs Sheeva you can substitute HK, LP, aaHPHP, spear, 3 hit, aaHP, JK, air throw for exactly 50%.
Ermac - 42-54% - vs Sheeva you should be able to get , HK, LP, TP, TKS, aaRH, TP, HK which is reasonable damage vs her, OR, you can attempt to relaunch her. Vs Shang, HK, LP, JK, TP, TKS, aaHPHP, JK is possible for 45%. vs most other characters you can add the optional extra aaHP in after the aaHPHP. Vs the large characters you can do HK, LP, aaRH, TP, TKS, otgHK, LP, aaHP fireball, and many other optional combos totalling up to 54% but become very complex and flashy. Remember using the aaRH in combos often times leads to very close corner proximity so utilize the corners to break into the 60s.
Nightwolf - 41-53% - Most reasonably vs Sheeva and Shang NW can get 41% with 5 hit, axe, HK, and up to 52% with 4 axe combos vs many characters, and then an example of 53% is vs Jax, 5 hit, axe, aaHP, axe, aaHP, tackle. There are various NW mid screen variations, some may even go a little beyond that. Also remember tackle lock down mix ups.
Kano - 23-47% - you can opt easily for Kano's 4 hit kick combo or HK, LP, JK, air throw and get pretty low damage, or you can his 3 hit knee lift pop up, optional HP before the JK to air throw on most characters for closer to 33%, a deep JK, to various options like LK, HK, or cannonball reaching up to 34%, or if you're very daring, vs some characters mid screen you can do 3 hit pop up, deep JK, aaLP, Manhandle, to LK or cannonball. VERY DIFFICULT but possible on about half the characters.
Sindel - 43-46% - 4 hit pop up, aaHP, (option second aaHP), JK, AFB. RJ scream mix ups are not as good as they might seem.
Classic Sub-zero - 19-46% - His 3 hit kick combo has an awkward way of performing it so you don't see it used very often, however using the first 2 hits while blocked is useful for mix ups. A common tactic is using his ground freeze during RJs, setting up cross up JPS, 4 hit pop up, deepJK, HK for 46%. There are various other 40% variations for him. Remember C Sub can easily relaunch many characters.
Sonya - 38-42% - 5 hit pop up, (optional aaHP), JK, leg grab - to rush down mix ups, or 5 hit pop up, JK (optional LK or HK)
Kabal - 30-42% - (optional Spin), 5 hit pop up, (optional aaHP), JK AFB. The spin is always a threat during RJs because the start up is so fast, resulting in reasonable damage mid screen and high damage in the corners.
Sheeva - 27-40% - knee lift 4 hit kick combo, potential Ground Stomp and Teleport Stomp mix ups, if you opt for the punch combo (remember it hits high), you can finish out to the 7 hit, or opt for juggles with the 4 hit punch combo. Sheeva's 4 hit kick combo is you key to victory in many cases on Sheeva rush down as everything else is counterable or avoidable. Sheeva also has good throw potential with throw to HK for 28%, or throw to uppercut vs Male ninjas, for 31%. Vs many characters a throw = a free unavoiable teleport stomp after the second bounce. Learn the timing, it's useful. Some characters can escape or counter it with special moves but throw - teleport stomp = 40%
Jax - 37-39% - 7 hit ground combo to ground pound, or, 6 hits of 7, (optional sweep, LK, or HK) into sweep tactics to Back Breaker. Mix up his sweeps during RJs in general as well to bait jumping into Back Breaker traps.
Mileena - 23-39% - 4 hit kick combo, 3 hit or 5 hit pop up, (optional aaLP), JK, air sai. Rolls or Teleport Kicks during RJs are not too smart but can result in small damage.
Kung Lao - 19-34% - Basically all you can get off a ground guard break with Kung are his standard chain combos. You can sometimes do a spin during RJ rush down and hope for a guard break but do not commit to the spin so it stops quickly. This may put you on the defensive but opens up more possibilities for Kung counters.
Unmasked Sub-zero - 19-34% - Very simple, rush, use his 3 hit kick combo, mix in Ice Clones and change to zoning, Close Air Freezes are sometimes ok to entice counters which will freeze them and worth the damage trade off, Freezes too but not often. If an Ice Clone or Freeze hits, use his typical large ground combos, or a deep JK to juggle.
Kitana - 23-31% - 4 hit kick combo to fan keep away, or 4 hit fan combo (optional sweep on male characters except Shang)
Robot Smoke - 19-31% - Stick to his three hit HK, HK, LP combo mixing up with RJs. You can occasionally throw out a Harpoon if expect a counter, but it isn't always the best idea. A Harpoon to 5 hit combo also leads to free invis before the combo so that is a reward for the risk. Some players even do invis during RJs followed by a Harpoon but that requires a committed pattern.
Sektor - 15-31% - 3 hit pop up, aaHP, (optional second aaHP) JK, into homing missile lock down, or his simple HK, HK combo.
Jade - 23-29% - 4 hit kick combo, or 4 hit staff combo, sweep (optional LK or HK on some characters)
Shang - 27% - knee lift 5 hit combo, into fireball lock down
Liu Kang - 22-25% - Liu's 4 hit kick combo can be used during RJs, but also remember the trusty Bike Kick's property for counters. If you connect it while your opponent is trying to counter you can connect a free Dragon Kick after it mid screen for 25%. Also remember that many times this counter Bike Kick will bring them to the corner, so afterwards do his 7 hit combo followed by optional unlockable sweep, LK, or HK depending on the opponent, resulting into up 48%.
Cyrax - 19-24% - simple 3 hit kick combo maybe be your best bet during rush down. You could throw out some semi risky nets during run jabs which puts him up to as much as 42% with a kick starter to 6 hit combo but that is inadvisable. Doing close bombs during RJs is a good idea, which makes your opponent jump away, then throw a long bomb. At this point they cannot rush you because the first bomb is about to go off, so use this chance to knock them back into the far bomb, resulting in much higher damage. If you get a throw with him, a possible combo is aaLP, Net, aaHPHP, JK for 24%, then do his air throw while they are falling to put Cyrax very close to them for more rushing and mix ups.
Scorpion - 23% - his knee lift kick combo is generally the only one you should use during RJs, leave out the last hit when blocked for recovery advantage, stick out a HK or LK to counter rush. I wouldn't advise throwing Spears while RJing. Sometimes during RJs you can do a teleport punch when it will not put you off screen, which baits rush down and in that situation you MAY want to throw a spear, or if they jump, RH, TP, spear, 4 hit combo for 37% (optional pause, RH, teleport back over them for further rush down - watch for counter uppercut on teleport). Going for damage use aaRH, TP, aaHP, (optional aaHP), Spear, 4 hit combo for 46%.
