5 cross-brand teams/stables that could be formed due to the Wild Card rule
Factions are an essential part of the business and can make or break a roster. nWo brought a lot of attention towards WCW and built up the roster as they provided the rub to other superstars who competed against them. But, at the height of their power, they denied losing to the superstars who needed to get over them.
At present, WWE is in dire need of a legitimate stable after The Shield disbanded. The Wyatt Family is a thing of the past and the New Day aren't a stable anymore with Big E out injured.
The closest WWE is to a stable on the main roster is the unnamed on-off team of Baron Corbin, Drew McIntyre, and Bobby Lashley. In spite of the criticism, they're the best stable in WWE at the moment on the main roster which includes the Lucha House Party.
With the Wild Card rule, WWE presents itself with a golden opportunity to bring in and push a dominant stable which can run over superstars across both shows.
While WWE could bring in the Undisputed Era but it would hamper their current storyline and might become a rush call-up with already a few rookies without a direction. Therefore, we would mainly focus on the superstars already on the main roster to create a cross-brand faction.
#5 Viking Experience (Viking Raiders, Sarah Logan, and Killian Dain)
Viking Raiders came to RAW with a ridiculous name change. They were War Raiders on NXT and came up to the main roster as the Viking Experience. Although, it was a great ploy to get their finisher over after they settled for Viking Raiders. They're the current NXT tag team champions.
On the other hand, the Riott Squad disbanded recently, and Sarah Logan made her way to RAW. She is married to one-half of the Viking Raiders, Raymond Rowe. Given her Viking background, she is the best choice for a female member in a Viking group.
Moreover, Killian Dain got demoted from SmackDown. If he comes back to the main roster, he can join the Viking Experience and even become their leader.