#2 Kevin Owens
Kevin Owens seemingly went from huge WrestleMania plans to no WrestleMania plans. After going down with an injury last October, former WWE Universal Champion Kevin Owens returned to WWE SmackDown in March, where he was named number one contender to the WWE Championship, and challenged Daniel Bryan for the title at WWE Fastlane.
Owens was heavily rumored to originally have these same plans for WrestleMania itself, before Kofi Kingston's popularity became overwhelming. Instead of challenging Bryan at WrestleMania, Owens was left off the WrestleMania 35 card entirely. He wasn't even given a spot in the André The Giant Memorial Battle Royal. That is one incredible drop for someone who was originally rumored to be in the WWE Championship match.
And I think, due to his involvement in the WWE title match at Fastlane, KO would have still fit right into the Championship match at WrestleMania just fine, and it should have been a Triple Threat. Sure, Kofi Kingston does still deserve the big win, but I think it would have had the same impact and been a better match, if Kevin Owens was involved also.