Introduction
One of the most common problems that newer players seem to have with 3rd Strike is the double QCF motion, which is part of virtually every super in the game. Even players with limited or no real fighting game experience seem to know about the fireball and shoryuken motions, and don't have much trouble mastering them, but the double QCF is a somewhat different beast altogether. It can feel arduous and requiring a lot more effort than other typical fighting game motions (QCF, DP, HCF/HCB, etc.), and trying to pull off combos like Yun's 1-2-3 (LP,LK,MP) xx Genei-Jin or Ken's MP, FP (strong-fierce) xx SAIII can be an exercise in frustration. Thankfully, there are tricks that can mitigate or avoid these frustrations altogether.
Double QCF? More like 1.5x QCF
When one thinks of the double QCF motion, it's natural to think that "double QCF" = 2 full QCF motions - D, DF, F, D, DF, F + punch/kick. However, the 3S engine actually interprets the DF (down-forward) positioning of the joystick as both "down" and "forward" for the purposes of a button press.
This actually has surprisingly large ramifications in terms of the joystick motion necessary to pull off moves centered around the fireball (QCF) motion. The double QCF motion, thanks to this mechanic of the 3S engine, can actually be compressed to D --> F, D --> DF + punch/kick, or something closer to 1.5x QCF. Similarly, a regular fireball no longer requires doing the full 90° QCF motion, but just a 45° D --> DF + punch motion, and the shoryuken motion is condensed to F, D --> DF + punch.
This may not seem like much of a difference to the inexperienced player; after all, the gap between DF and F is fairly small, right? However, when it comes to pulling off tight combos like the 1-frame, crouching only combos mentioned in the previous post, the difference between DF and F goes from seemingly insignificant to actually quite important! In addition, more advanced tactics like punishing whiffed normals with Chun-li SAII or Ken SAIII involve very strict timing where good reaction time simply isn't enough - every frame counts, and minimizing your joystick motion by a frame or two can be critical. Even from a strictly mathematical standpoint, a fireball now requires half as much motion as before! How can that be anything but helpful?
Buffering the first QCF into another move
Ok, so we've found a way to cut down on the amount of joystick wiggling necessary to get a super to come out. But even so, double QCF is still a fairly unwieldy motion as a whole, still requires 3 directional shifts to come out. Is there anything else we can do to make getting supers out less difficult?
As it turns out, there is. Another mechanic of the 3S engine which most beginners aren't familiar with is the following:
Joystick inputs for one move will also count towards any subsequent moves in the near future.
As far as the double QCF is concerned, this means that the QCF involved to do, say, a fireball will also count towards the double QCF requirement for a super. So fireball xx super (say with Ken) becomes:
QCF, P --> QCF, K
In effect, you are "hiding" the first QCF requirement in another move which you execute before the super itself. The end result feels a lot smoother, since it involves a nice alternation of joystick movements and button presses, and the end result is akin to back-to-back fireballs rather than a complicated joystick movement followed by a button press. The whole thing still has to be executed quickly, but it feels a lot less clunky on the whole. Here are some common combos that use this technique:
1. b.+HP xx HCF+P (fireball) xx SAII (Chun-li)
2. cr. MK xx QCF+P (fireball) xx SAI (Akuma)
3. st. MP, HP xx QCF+P (fireball) xx SAIII (Ken)
The first two combos (back-fierce super with Chun, low-forward super with Akuma) are actually not very hard to do, even if the fireball is omitted; these combos utilize the extra fireball primarily for extra time to hit confirm. Just as I mentioned buffering QCFs so that you have less to do after seeing confirming the initial hit (just a button press) in my hit-confirms post, throwing out back-fierce xx fireball or low-forward xx fireball leaves you with only one more fireball motion to input for a super after confirming the hit. Both of these are somewhat tighter hit-confirms if you try to do them straight up (especially shoto low-forward, in general), but become much easier with the extra buffer from the fireball. Of course, the downside is that you leave yourself open to having the fireball parried and then getting punished, so you can't just throw in extra fireballs willy nilly, or exclusively use it as a crutch for poor execution or reaction time.
The third combo takes a combo that requires fairly quick hands (strong-fierce-super) and make it much easier to input. You do lose a point of damage because of damage scaling, but you gain a tiny bit of meter as compensation, so all in all it's a roughly even result either way.
Tackling the double QCF beast head on
So far, we've been covering ways to make life easier when comboing into supers, and that's fine and dandy up to a certain level. However, at some point you will run into stuff that you can't skate your way around, like 1-2-3 xx Genei-Jin or strong-fierce-super with Ken; there will be times when you want that 1 extra point of damage over strong-fierce-fireball super, or you just want to become a better player and develop the hand speed necessary to do the optimal combo at the optimal time.
Unfortunately, there's very little one can write on this point, other than "do the double QCF as fast as possible, as soon after the button press as possible" that can really elucidate matters much further. (Of course, I'm still going to try!) A video would be a lot more helpful in this situation, and I hope to make videos to supplement these posts some day, but unfortunately I just don't have the time or resources to do so at the moment.
The best I can do in trying to explain how to pull off the double QCF in combos like the aforementioned ones is as follows:
Whenever you do something involving multiple button presses, say Ken's strong-fierce chain or Akuma's Raging Demon, you're more likely to think of each press as a discrete input. On the other hand, when you consider something like a simple fireball, you generally don't think of it as two discrete motions, not "QCF, then P". A fireball generally feels more like "QCF into P" - like one, smooth, continuous process.
Doing a combo like Ken's strong-fierce-super, you have to think of fierce xx super in the exact same way, only in reverse. Instead of a joystick motion tapering into a button press, it's a button press flowing into a joystick motion. Just as the gap between the end of "QCF" and "pressing P" is more or less imperceptible for a fireball, "pressing fierce/HP" should be followed virtually immediately by the first QCF, as if "HP into QCF" into D --> DF is one continuous idea. That's the best description I can give for the time being.
Hopefully this post has made it clear that the double QCF is not quite the intimidating beast it may initially feel like, and with a little practice you can master the various techniques involves with the motion until it feels completely natural.