Floor stomps are never guaranteed in DOA5, AFAIK.
Free Step Dodge
Lulu
If you mean the Pounces.... yeah.... those take to long to connect. I do however believe certain light ground attacks are guaranteed..... I can't be sure though. I never considered them worth Testing.
Brute
Nyo's 8P+K functions like the "pounces" so yes, that's what I'm referring to.
Camel with 2 thumbs
so far every setup i've use to land the 8p+k it loses to forward roll, hard knockdown or not,and if this thing can beat tech rolls, it makes me wonder if you can 100% it, but this aint DOA4 so maybe you can't, but dammit ill keep trying
Brute
"Floor stomps are never guaranteed in DOA5"
--Brute, 2015
--Brute, 2015
Camel with 2 thumbs
"Never say never"
--Justin Bieber, 2011
--Justin Bieber, 2011
Brute
My ethos is just a bit more reputable than Mr. Bieber's, I imagine.
Camel with 2 thumbs
probably 
Okay so my reccomendatiom is to find out exactly how another Character gets a hard knockdown into a guaranteed ground attack or force tech......... which people keep telling me is possible but I haven't seen it yet...... except from Bass.