#2 Shawn Michaels
If there's one legend that is most qualified to be a special guest referee from this list, it is Shawn Michaels. HBK has been a special guest referee on numerous occasions in WWE, refereeing as recently as last year in an NXT match between Drew McIntyre and Adam Cole for the NXT Championship in 2018.
Michaels has refereed high-profile matches in the past, including a match between The Undertaker and Triple H WrestleMania XXVIII, which The Deadman won.
From a storyline point of view, this makes sense. Michaels can be aggrieved that Batista attacked his hero and idol in Ric Flair, while also wanting to help his good friend, Triple H, win the match.
Michaels, like The Rock or Vince McMahon, would add tremendous star power to the match, and his antics in the ring could make for exciting viewing.