Deciding if a match is a stomp is often a case-by-case basis.
If it's a case of they "won't" win because the means to do so are severely OOC, then I'd think that's a stomp against them when they AREN'T bloodlusted. I assume that generally, in such a case, it would only not be a stomp if they are bloodlusted.
Quoting
https://vsbattles.fandom.com/wiki/Bloodlust :
"A bloodlusted character will not be victim to
Character Induced Stupidity, and will be much more likely to speed blitz opponents (if doing so is within their powerset)."
In theory, there may be cases where a character won't or can't win even with bloodlust, given the limitations of how it affects characters. But that's theoretical. Also, case by case.
Regardless, the point is, VSBW does HAVE some accomodation for characters to act very OOC for Versus Matches. With that in mind, matches participants WON'T win at all, because of their regular behavior when acting IC/not bloodlusted seem like they could be treated as stomps, IMHO, supposing being OOC/bloodlusted would allow them a reasonable chance to win.
And matches where it's not that they won't win, but CAN'T win, even being OOC/bloodlusted would also be stomps.
(In theory, there's also knowledge/preptime based stomps, where a character can't win because of something they don't know or can't/won't know.)