Even if mirror matches are jokes within the guilty gear universe....what is the story be behind the each fighter having their own clone(based on their outros)? after all, it's not like anybody could copy them beat for beat at best. Also assuming those clones are one and the same...what kind of color palette or differences can let their friends tell the original and clones apart?
You ask a difficult question... not simply because Mirror Battles don't have a strong position in GG Lore, but because we don't know every instance of them (i.e. we don't have Strives' full roster to say for certain what each mirror quote/s is like).
Even based on videos that have covered the topic as much as can be done... we still don't have DLC characters, nor can we assume that anyone or everyone from previous games will return.
Up until now, Mirror Matches have mostly been defined by funny end Win-quotes... Strive is the first game in the series to actually create intros to suggest characters are fighting their copies.
Perhaps it's a nuance that Ishiwatari wanted to implement in his older games, but somehow couldn't due to technicalities.
At best, I can only state that it only serves to share a little additional insight in to the respective characters, their motivations and personalities, and the respective nuances that have developed them as characters.
As for colors, that has always been random and arbitrary. Sometimes mirror colors reference older games in the series (like Raven's GG2 Overture colors or Millia Rage's GGX color pallet), and sometimes they reference other things entirely (like BlazBlue characters).
It has been joked though, that Sharon had a *VERY* hard time telling Slayer from his clone apart!
