  Getman et al. (2021) reports the discovery, energetics, frequencies, and
effects on environs of $>1000$ X-ray super-flares with X-ray energies $E_X \sim
10^{34}-10^{38}$~erg from pre-main sequence (PMS) stars identified in the
$Chandra$ MYStIX and SFiNCs surveys. Here we perform detailed plasma evolution
modeling of $55$ bright MYStIX/SFiNCs super-flares from these events. They
constitute a large sample of the most powerful stellar flares analyzed in a
uniform fashion. They are compared with published X-ray super-flares from young
stars in the Orion Nebula Cluster, older active stars, and the Sun. Several
results emerge. First, the properties of PMS X-ray super-flares are independent
of the presence or absence of protoplanetary disks inferred from infrared
photometry, supporting the solar-type model of PMS flaring magnetic loops with
both footpoints anchored in the stellar surface. Second, most PMS super-flares
resemble solar long duration events (LDEs) that are associated with coronal
mass ejections. Slow rise PMS super-flares are an interesting exception. Third,
strong correlations of super-flare peak emission measure and plasma temperature
with the stellar mass are similar to established correlations for the PMS X-ray
emission composed of numerous smaller flares. Fourth, a new correlation of loop
geometry is linked to stellar mass; more massive stars appear to have thicker
flaring loops. Finally, the slope of a long-standing relationship between the
X-ray luminosity and magnetic flux of various solar-stellar magnetic elements
appears steeper in PMS super-flares than for solar events.
