They will fail to make anything remotely as cool as Bullet Club just to be straightforward. Whether it be the current 4th wall breaking silly incarnation lead by Kenny Omega, the original lead by Fergal, or the perfect blend of the two A.J. Styles. What made them so unique, to begin with, was that the general idea of the stable was taboo. On inception, they had already done something relatively unheard of and provided kind of a blurry window to both Japan and the United States pro-wrestling landscapes. It does benefit WWE that they've positioned Balor to be the leader of a group with ties, but a bit of a different group altogether rather than Styles or Omega. Finn Balor being a few years younger than Styles gives his some more time in the tank. Also, his in-ring style while inferior in physicality to both Omega's and Style's leaves him the ability to perform at a higher level than most for a bit longer in his career. Relying more on psychology than flash and moves never hurt any of the biggest names in the business for sure.
So let's go to dreamland and I will try to fantasy book this out a bit in my head to provide some kind of unique input or something satisfactory.
A big mistake NJPW has done with Bullet Club and why they are somewhat failing on their original platform (Partially cause Naito and his stable are super cool and over) is making Kenny Omega such a big deal. While it's hard to keep down such an enigmatic wild character and great wrestler it's ended up hurting the Bullet Club as a whole. They do shine on other platforms, but they've failed a bit at being unique and innovative which is what made them such a big deal, to begin with. Instead of producing new stars from the stable the current roster of Bullet Club members consists mainly of people who had already made it prior and are foreigners. (Marty, Cole, Cody, Hangman Page, etc.) Why this isn't exactly applicable to WWE the point really is that too much outside interference to distort the objective of the group completely dilutes the point.
So looking at Balor and all of his potential as a heel (great track record) it'd definitely be good to make them more serious with a hint of silliness or fun. How he smiled casually at Kurt Angle and then pointed back at Karl & Gallows to say "Nerds" was actually a somewhat shallow but good example. So we could literally continue this next RAW or have them pop up again a little bit down the road to Wrestlemania and work towards a formation or debut angle or whatever. Balor has a lot of personality despite a lot of people finding him rather boring as of late, but there is literally no way he can carry two guys with a really dry niche sense of humour and appeal to being entertaining.
So let's add one or two people and not go any further because when you hit a stable with over 5 or 6 people you really start to stray away from an objective. The objective is important, because without a cause or something to believe in pro-wrestling just does not work. It's what made The Shield flourish, and The Wyatts drown. I don't see them being a type of stable to wipe out literally everyone on the roster in some shocking debut or anything. I picture them helping out their friends in the stable, wanting to have fun and make money, and being heels even to other heels. Even the most shallow of objectives are objectives and work if they are dealt with. A good example is Braun Strowman and even Daniel Bryan.
So who is slick and disregards people. Elias. He has a unique gimmick and is an absolute heat magnet. His style isn't exactly dark, but it definitely strays far from the light and really enters those shades of grey that Balor and "The Club" dwells in. So that's a tag team, a leader, and your token underboss Bad Luck Fale type that glues the team together and can kind of do everything. Then we don't really need a female. It'd be cool to see something like that. Especially looking at Nikki Cross as kind of a really far out example of how you can incorporate a girl into a hyper-masculine / edgy stable. I'd honestly of thrown Paige in there as a legit female competitor, but not so much anymore. Asuka is a good choice I guess. Pretty shallow reasoning, but she'd probably fit what the general aesthetic that WWE would go with well. Being undefeated doesn't hurt either.
for the last guy, I'd just throw in a dude that you can use to basically destroy the faction from within or use as a multi-purpose tool to advance storylines to the greater good. Kind of like how Kenny was groomed over time to take over for Aj Styles. Not to break them up (although you know WWE LOVES to do that in recent years) only per say, but to have that *Seth Rollins turning on The Shield* trigger ready. It just comes in handy. Every Goku needs a Vegeta.
Note: Post is total mess. This does not accurately represent my functional brain.
