The way I have peach move in tiny increments is totally and completely unrealistic for any actual match. Basically depending on how you time jab transitions, peach slides forward a minuscule amount.
Gonna throw in the towel on testing the phantom d-smash vs. Jigglypuff in rest lag. If Phantom d-smash is at all realistically possible it would be in doubles when your partner gets a grab. There are lots of other more productive things to work on though, hitbox analysis and KO% testing with DI, etc. When I used to do this sorta thing for brawl (oh the shame... don't judge me bro), I really neglected practicing the bread and butter stuff myself, so my output isn't gonna be as absurd as it was 2 years ago. I definitely want to have the tech skill, spacing, and understanding of practical strategies, rather than just being a ridiculous math junkie.
Question for you Peach's: Is there any reason to wavedash forward as opposed to just using her DJC landing (whatever its called). I just roll my finger over the jump buttons, or hit Y and use my thumb to press x, and it feels way faster than the wavedash. I know that from the raw frame data perspective it IS better, but I'm not exactly an excellent judge of distance.