Okay, I asked this question in the other thread:
This actually prompts two Egg Lay related questions: does swallowing a target cause the move to have different frame data, and what's the formula for an opponent breaking out of the egg?
After investigating this in develop mode, I have the following findings:
Yoshi always executes the first 19 frames of the Egg Lay animation. Keep in mind that Egg Lay has a grabbox frames 17-21. After the first 19 frames of the animation, or when the grabbox makes contact with a target, whichever is later, Yoshi then has a 30 frame animation where he swallows the target and poops out the egg. This animation is independent of the target's weight - I tested this with Bowser and Pichu. This animation can't be interrupted by a jump, and I don't think it can be interrupted at all.
The target is ejected as an egg on frame 26 of the pooping animation. I
think the target can begin inputs to escape as early as 2 frames before he becomes an egg; not sure on this. I didn't test this extensively.
A target that doesn't attempt to mash out at all will be trapped in the egg for 199 frames (YoshiEgg) and will break out into the Fall animation on frame 200 if they haven't. If the target is inputting A/B/X/Y/up on the frame before he breaks out of the YoshiEgg animation, then he will break out directly into a double jump or an attack depending on the input. The YoshiEgg animation is an 8-frame loop that goes from 0 to 7. The first frame of the YoshiEgg animation when the target is pooped out is frame 1 of the animation, not frame 0 - it goes from 1 to 7, then it loops repeatedly from 0 to 7.
The YoshiEgg duration seems to be independent of the target's weight and %. I tested Bowser @ 0%, Pichu @ 0%, and Pichu @ 108%. I don't have enough time to test how mashing reduces the YoshiEgg duration such that I can come up with a formula (see EDIT), but I do have some useful results.
If the target mashes 1 of A/B/X/Y every frame, he will be trapped in YoshiEgg for 13 frames and escape on the 14th.
If the target inputs a direction on the control stick every frame, he will be trapped in YoshiEgg for 13 frames and escape on the 14th.
If the target mashes 1 of A/B/X/Y every frame
and inputs a direction on the control stick every frame, he will be trapped in YoshiEgg for 6 frames and escape on the 7th.
The L/R buttons, C-stick, and D-pad have no effect on YoshiEgg duration. The target cannot input 2 of A/B/X/Y on a particular frame. I'm pretty sure the Z button does nothing as well, but Z frame advances in develop mode, so I don't know how to test.
Finally, Nana. Nana actually does seem to mash a tiny bit right when she enters YoshiEgg. Nana is always trapped in YoshiEgg for 185 frames and will break out into the Fall animation on frame 186. Popo's inputs have zero effect on how long Nana is trapped in YoshiEgg.
EDIT: So based on this information. I have the following hypotheses. Each input reduces the duration that a target will be trapped in YoshiEgg by 14 frames. This is based on the fact that Nana escapes from YoshiEgg 14 frames faster than a target that attempts no inputs at all (correlating assumption is that Nana attempts exactly one input, presumably so she can fall towards Popo). Additionally, inputs take effect starting the frame
before YoshiEgg comes out. This is based on the fact that assuming 1 input = 14 frames, there needs to be 14 inputs for a frame 14 escape and 7 inputs for a frame 7 escape, which is consistent with the data. I don't have the time right now for further testing to confirm this.