#1 The Demon King

Not really a partner, but an alter ego nonetheless. Fans choose to think of The Demon as another Finn Balor, and we could watch him unleash The Demon on Lashley.
Balor would not be happy with his loss and could come out as The Demon to take on Lashley and Lio Rush himself. This would allow him to bring back the character once again with a storyline.
We saw The Demon at SummerSlam 2018 last, and since then fans have been speculating when The Demon will return.
WWE has already used Finn Balor’s Demon persona for WrestleMania 35 promotional materials, and it could be a sign that Balor will indeed fight as The Demon at WrestleMania.
Hence, if WWE is going to have Balor bring back The Demon for WrestleMania 35, then it would be perfect if they give the fans a taste of what he can do against Lashley and Rush.
There is no reason to doubt that WWE is going to give the fans a surprise, and that’s why they haven’t revealed who Finn Balor’s partner would be.
Major rumor about recently released stars HERE