Wouldn't it be awesome if Forbidden Door legitimately was a cross promotional major event? Like AEW+WWE+TNA+NJPW+Stardom? I could mention some other companies too, but those are the big five and honestly I could probably drop TNA from that list, but to their credit Kenny Omega has performed there and two of their women's champions have appeared in a WWE Royal Rumble so I feel like they'd be worth having in a dream scenario like this. This event could legitimately be a two night event. So many fun potential matchups:
Asuka/Kairi vs Shida/Riho - A joshi fan's dream match
Charlotte Flair vs Mayu Iwatani for the IWGP championship - Because Charlotte doesn't believe she's had enough championships already in WWE LOL. The heel/face dynamic would be beautiful (Charlotte being the heel of course)
Mercedes Monet vs Tam Nakano - This is one we may actually see in real life at some point, especially since Monet/Giulia may potentially never happen
Jordynne Grace vs Bianca Belair - Power battle
Becky Lynch vs Giulia - These ladies have a lot of similarities in their personality
Jamie Hayter (with DMD) vs Rhea Bloody Ripley (with Dominick) - At some point in this match, I'd have Dominick try to interfere only for DMD to knock him on his ass. Crowd would lose their goddamn minds
Mike Bailey vs Shinsuke Nakamura - No DQ because I need to see Shinsuke with nunchuks damnit!
Gunther vs Orange Cassidy - Oh my god, Gunter would be so offended by EVERYTHING that is Orange Cassidy
AJ Styles vs Jay White - Gotta love seeing the former Bullet Club leaders go at it
Roman Reigns vs Kazuchika Okada - The pride and joy of two companies (past tense in Okada's case) going at it.
Seth Rollins vs Kenny Omega - Two weird guys who are awesome in the ring
Brock Lesnar vs Will Ospreay - I think a face Ospreay bumping around for a heel Lesnar could be awesome. Lesnar would of course have to BRUTALLY DESTROY HIM at some point before the actual PPV, because that's how you book Brock Lesnar.
Chad Gable versus Daniel Bryan - You could potentially put Zack Sabre Jr. in Bryan's spot too, a technical masterpiece waiting to happen.
Sheamus vs Tomohiro Ishi - Hard hitting, manly fight that will leave both men in pain for days.
Meiko Satomura vs Serena Deeb - Deeb + joshi wrestlers = awesome matches
CM Punk versus Hangman Adam Paige - This just writes itself
Kevin Owens vs MJF - My God, the promos!
Sami Zayne vs Adam Cole - Cole has to be full heel for this match
The Young Bucks versus The Usos - Super kicks for everyone!
Timeless Toni Storm vs Maki Itoh for the Lulz, speaking of which
Special appearance from DDT giving us the following match:
Yoshihiko vs R Truth for the 24/7 title and the Ironman Heavymetalweight Championship


Oh, and one last match:
Stardust versus Fuego Dos because:
A) It would be goddamn hilarious and
B) "Fuck your story"