Hey everyone, found this place a little while ago, great discussion, really wish there was more of this out there. I don't mean to brag, especially on my first post, but I have been practicing the DJC for several years now and I feel as if I have some sort of mastery of it. At first, I could only do DJC + d-air because I was not jumping twice fast enough. D-air is more forgiving because you attack down afterwards (obviously, it’s d-air), so even if you don’t perfect the timing of the DJ, you are forgiven because Ness’ d-air has enough range where you can be moderately elevated and the hitbox still touches at least the opponent’s head (it is also forgiving because of the lack of cancelling). After I started getting the hang of this, I began to learn DJC + f & b air. B-air is extremely valuable because of its long range, relative to the short range of Ness’ other air moves, especially f-air and n-air, in which the hitbox barely extends past Ness’ torso. Pressing (C + C + joystick L or R + R + air move direction) allows you to slide across the level a certain distance, while extending the distance with further with the range of the b-air. If perfected this can be more effective than Ness’ dash A, which also covers horizontal distance but has delay afterwards. Once you begin to get the hang of DJC, which is essentially just C + C + R + direction of your choice, you can begin to try DJC n-air and u-air. N-air is difficult because the hitbox has such poor range that you must use it immediately after jumping to hit an opponent, and it needs to be well timed because the opponent must be close. Obviously all the DJCs are easier on taller characters such as Samus or DK; to hit Kirby or Jiggly with a DJC n-air is difficult. Maybe it’s best to practice on the tall characters first, although I do not remember doing this specifically. DJC + n-air is also very valuable for tight spaces, such as next to the steeple (or whatever it is) in hyrule. Ness benefits from the all-encompassing hitbox in close quarters. The most difficult though, is of course DJC u-air, for several reasons. One, the hitbox is ABOVE Ness, so you must be in the air while still being below or at least eye level with the opponent. Also difficult, you must press up on the joystick to perform u-air. Therefore, if the timing of pressing the buttons is not correct, you will float upwards more than you want, as pressing up for and intended u-air with the wrong timing, can become a jump instead. This is not the case with DJC d-air, as pressing down at the wrong time won’t change the outcome as heavily.
Combos; The DJC + u-air is valuable because it can initiate juggling combos that are impossible to escape if the opponent is at a low percent or heavy. DJC + d-air is a great combo too, but it can easily be rolled out of. The best way to use DJC + d-air, in my experience, is on a small platform, where the opponent can only roll away to the sides of the platform (ie, the central elevated platforms in hyrule). You can reach the side of the platform at the same time that your opponent does, and initiate another DJC + d-air before they can escape, leading to huge combos. This is theoretically possible on any surface if you can immediately predict which way your opponent is going to roll after the initial DJC + d-air. If you can dash over to that area with Ness first, and reach the location where the roll ends at least at the same time as the opponent, you can initiate the next DJC + d-air. I hope this makes sense, I do not profess to be exceptional at this game because I haven’t played a wide variety of people, perhaps there are strategies that I am unaware of to escape or heavily counter the techniques that I am describing.