Continuing the story conversation of Mature and Vice from he OT3:
Vice and Mature are Dead, so says so in the KOFXIII Iori Team Story. Their sprites also have a "Ghostly" color pallet, making reference to it. If that is not enough, Iori Team ending in XIII has them as ghoslt pictures talking to Iori when he is making the choice in picking up his flames again or not.
The spectre pallettes could be taken as seriously as the cosplay ones could be, simply just there to poke fun at their speculated death and disappearance. It also never states in the Yagami Team's story that they were indeed dead.
Also, in their ending I suppose you
could interpret their appearances as looking "ghostly"; but we all know ghosts can't physically harm people ~ which they obviously can.
I interpret the ending as Mature and Vice doing their signature "fading into the shadows" as they bid Iori adieu until "the next full moon" which they've done previously.
SNKP stated they were "left for dead" and subsequently went "missing" after Iori's rampage, they most likely purposely keep Mature and Vice shrouded in mystery with Iori saying things like
“… What business do dead-like people have with me?” and having their prologue mention that
"Vice and Mature, both are supposed to have been killed at Iori’s own hands." It was never officially stated the two had died and there is absolutely no mention of them being resurrected in their KOFXIII stories, just nods to their abilities to appear and disappear at will.
Vice: “Originally we weren’t planning to come out.”
Iori: “Then, why are you here?”
Mature: “Well, I wonder why… Could it be because you were disappointing beyond expectations?”If they were indeed killed, SNKP would have just outright stated that; which they didn't. So using in-game statements and events, I think it's fairly safe to assume that the two were indeed
left for dead -as officially stated- and not actually killed, but simply withdrew until they were needed.