I'm having am extremely hard time reading and understanding this all. I'm trying to parse dtilt right now.
Okay, so I finally took the time to figure out all this crap...D-tilt is a rather complicated move to break down, because it serves several purposes. It was even more complicated in 3.0, but in either case, here's what you need to know from a "how to use this in combat" standpoint:
1. meteor on grounded opponents, which makes it a great combo starter
2. toe sends aerial opponents up
3. hip is a meteor on grounded opponents
4. Using multiple d-tilts in a row is bad, because you can't act as fast
I understand the move has 4 hitboxes (though not which hitbox goes with which number). They appear on the listed frames, deal the listed damage, and have the listed IASA frames.
Is there someone who understands it and could explain to me everything else?
D-tilt has effectively 2 "hitbox states." The first being frames 5-7, and the second being frame 8.
I'm going to break this down frame by frame. On frames 5-7, there is effectively one, single long hitbox that stretches across the bottom. This hitbox has Hitbox ID 0, which means it has highest priority. That actually doesn't mean too much, though, because it only hits grounded characters, and the others are aerial-only. SO, if you hit a grounded character with d-tilt on frames 5-7, they get meteored by that hitbox. It is also important to note that this hitbox is very low to the ground, which makes it the best choice for shieldpoking.
Against aerial foes on frames 5-7, one of two things happens. They can get hit by the higher priority toe hitbox (ID 1) and get popped up, or they can get hit by the lower priority hip/thigh hitboxes (2/3) and get meteored.
Frame 8 works only slightly differently. The hitbox that normally was very low to the ground to shieldpoke grounded foes reaches out a bit more, for the sake of coverage. It is a much larger hitbox with much more range, and it covers the same space as the previous toe hitbox. Additionally, hitboxes 2/3 that previously only hit aerial foes will now ALSO hit grounded foes (yay! coverage!)
The big toe hitbox that sends aerial opponents up works the same on frame 8.
So I hit my opponent with e.g. The toe on frame 8. Strongbad said (I think) that hitstun is 0.4 times knockback. So they take (30 + 0.55 * %) * 0.4 frames of hitstun, i.e. 12 at 0%. I have to wait 17 frames (til frame 25) to act out of it, so I'm -5 frame advantage on hit (and also on shield, because it has 6 frames of shieldstun). There's 6 frames of hitstun, but it doesn't matter to me because I'm waiting 17 frames to act anyway, so the 6 frames in this case just mean my opponent has 6 frames to SDI.
Although the hitstun formula is Knockback*0.4, the knockback formula is
much more complicated than that. I would recommend using
Strong Bad's Knockback Calculator. Most importantly, what you did does not factor in the amount of damage the move does. At 0%, most characters would take 17 frames of hitstun, which makes it +1 on hit (assuming we hit on frame 8), as you are actionable on frame 25, whereas they are still in hitstun. Additionally, it would be -13 on block (because let's be real, how on earth are you going to whiff their shield for the first 3 frames of the attack?). Both of you suffer hitstun, then your opponent suffers 6 frames of endlag, they are actionable on frame 5+6+1 (12) and you are actionable on frame 25.
And if I wanted to follow up with dtilt, I'd be waiting another 5 frames to connect, (assuming my opponent was back on the ground), so I'd be -10 frame advantage to hit with the second dtilt.
-4, for reasons discussed.
AND NOW THE FUN PART
So you would never want to follow up d-tilt with another d-tilt. You always have a better option. D-smash, grab (to beat a buffered shield), and up-tilt are the BnB. F-smash and Fair are also possible, depending on circumstances.
D-tilt's lowest hitbox doesn't like to show up in debug mode
Use the va-jay-jay hitbox to meteor Marth when he tries to recover. At low%, you can CC > d-tilt meteor him.
D-tilt is a god at the ledge even if you don't get the meteor, because you can get things like d-tilt > run off > fair, or d-tilt > d-smash. It's also one of her lowest reaching moves
D-tilt meteors grounded opponents. This is significant, because it means they get "stuck" on the ground. It beats CC, and they have to go through that dumb "stuck in ground" animation, which means mucho follow-ups