gravedigger
Dark Match Jobber
In my opinion, the only logical choice is Undertaker vs HHH vs HBK. It needs no explanation and there is a story there to be told and HHH and HBK could carry the match if Undertaker wasn't physcially capable. The Undertaker's streak is everything in regards to Wrestlemania and for the big 20-0 match, and possibly even his last match, he needs a big challenge and a big match and bar Stone Cold, Cena and Rock, nobody other than HBK and HHH are worthy of the honour.