Late reply but anyway i will TRY to find answers in your questions.
Clark: Vulcan punch is -3 on block if no hit whiffs and also creates some space so most character can’t or have a hard time punish it, also i am pretty sure Ex version is 0 on block and doesn’t create space so you can mix up after it. Also all version can be used in combos.
Gatling attack is just for combo as far as i know.
Special grabs are what makes Clark strong all versions have its uses.
Ralf: to be honest i am clueless about ralf so i can’t help you a lot.
A and Ex version of burning knuckle can be made safe on block if you hit them from a specific range. The range is different for each specific version (EX is almost whole screen so not really usful) so you can throw them if you think your opponent may try something from that range without the fear of being punished. Generally with Terry you want to stay in his optimal range when you are not attacking which is the range that A burning knuckle is safe. If the opponent jump, anti-air them with standing C, rising tackle, crack shoot or burning knuckle. Keep the pressure with fireballs. Also crack shoot is safe on block and a good antiair and can be plus on block if you opponent blocks it crouching so you can be trigger happy with it.
King: tornado kicks are all punishable as far as i know, only heavy version is safe from a specific range i think. with light version the second hit whiffs if you are crouching so you can even whiff punish it easily.
Kula: the light version is punishable from close range, from a specific range it can be made safe, the heavy version is tricky. If you are close range and you crouch she simply whiffs, further away she is -3 and she is safe but with clark you can punish her with your grab, if she is evern further she is completely safe since a command grab can’t reach her after block but from this range if you react neutral jump you can beat her with an air to air.
If you block it she can do an aditional move , the heavy version which is super punishable and the light version that is -1 on block and knocks you back so she is safe but if you are in corner with clark you can still punish her with a grab, even if she tries the adition move your grab come first so there is no reason to let her do it if you can grab her. The ex version is +1 on block and the aditonal moves after EX are the same as heavy version.
Kim: Air hangetsuzan can be punishable or plus on block depending how high you were hit by it. Most of the times its really tricky or can’t be punished but most anti air buttons can beat it. Fro example a common thing that Kim players do is getting a hard knockdown safe jump with a jump A and air hangetsuzan. That is two overhead attacks and he is plus on block but if you know air hangetsuzan is coming if you poke beteween A and air hangetsuzan you can beat it.
Now for Air CDs, there isn’t a simple solution for air-to-air or air-to-ground game on KoFXiii, it depends on the situation. The range, the type of jump ,the opponent and your choices. Some simple things is:
React anti air it with rising tackle with Terry.
Use light version of Clark’s command grab it will absorb the CD attack and grab him after, keep in mind that your opponent can avoid this if he can predict it.
Predict the jump and jump first with your own CD or good air-to air button.
Predict the hop and neutral jump with a good air-to-air attack.
If you opponent press the air attack to early stay crouched and trip guard him as he whiffs.
Predict the jump and meet them with Clark’s air throw.
React with a roll and get out of there, you will be better prepared next time.
Spend a bar and Blow him back after blocking so you neutralize the game.
Predict a jump with Terry and throw a crack shoot, even if you guessed wrong you are still safe on block.
There are many more things that can work depending on the situation.