That, my friend, will never happen.
people said that about model importing. (I'm pretty sure)
and I think it would be so that you would need to have 3 different files for someone.
EX:
If roy vs marth = marth load files for a character port over yoshi
if roy vs marth vs yoshi = marth load files for a character port over jigglypuff
if roy vs marth vs yoshi vs jigglypuff = marth load files for a character port over ness
if roy vs marth vs ness = marth load character port over yoshi
if marth vs roy vs jigglypuff: marth load character over yoshi
if marth vs roy vs yoshi ness: jiggly
if marth vs ness vs jiggly: yoshi
whoever codes this is epicness