What If the WrestleMania was the WWE Champion facing the rival company's World Champion
WWF VS WCW (1985-2001)
WrestleMania: Hulk Hogan VS Ric Flair
WrestleMania 2: Hulk Hogan VS Ric Flair
WrestleMania III: Hulk Hogan VS Ric Flair
WrestleMania IV: Vacant VS Ric Flair
WrestleMania V: Ricky Steamboat VS Randy Savage
WrestleMania VI: Hulk Hogan VS Ric Flair
WrestleMania VII: Sgt. Slaughter VS Ric Flair
WrestleMania VIII: Ric Flair VS Sting
WrestleMania IX: Bret Hart VS Vader
WrestleMania X: Yokozuna VS Ric Flair
WrestleMania XI: Diesel VS Hulk Hogan
WrestleMania XII: Bret Hart VS Ric Flair
WrestleMania 13: Sid VS Hulk Hogan
WrestleMania XIV: Shawn Michaels VS Sting
WrestleMania XV: The Rock VS Ric Flair
WrestleMania 2000: Triple H VS Sid Vicious
WrestleMania X-Seven: The Rock VS Booker T
WWE VS TNA (2002-2019)
WrestleMania X8: Chris Jericho VS Dan Severn
WrestleMania XIX: Kurt Angle VS Jeff Jarrett
WrestleMania XX: Eddie Guerrero VS Jeff Jarrett
WrestleMania 21: JBL VS Jeff Jarrett
WrestleMania 22: John Cena VS Christian Cage
WrestleMania 23: John Cena VS Christian Cage
WrestleMania XXIV: Randy Orton VS Kurt Angle
WrestleMania 25: Triple H VS Sting
WrestleMania XXVI: Batista VS AJ Styles
WrestleMania XXVII: The Miz VS Sting
WrestleMania XXVIII: CM Punk VS Bobby Roode
WrestleMania 29: The Rock VS Bully Ray
WrestleMania XXX: Randy Orton VS Magnus
WrestleMania 31: Brock Lesnar VS Kurt Angle
WrestleMania 32: Triple H VS Drew Galloway
WrestleMania 33: Bray Wyatt VS Lashley
WrestleMania 34: AJ Styles VS Austin Aries
WrestleMania 35: Daniel Bryan VS Johnny Impact
WWE VS AEW (2020-2026)
WrestleMania 36: Brock Lesnar VS Jon Moxley
WrestleMania 37: Bobby Lashley VS Kenny Omega
WrestleMania 38: Brock Lesnar VS Adam Page
WrestleMania 39: Roman Reigns VS MJF
WrestleMania XL: Roman Reigns VS Samoa Joe
WrestleMania 41: Cody Rhodes VS Jon Moxley
WrestleMania 42: Cody Rhodes VS Darby Allin